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It is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware.
Patches
For Next.js 15.x, this issue is fixed in 15.2.3
For Next.js 14.x, this issue is fixed in 14.2.25
For Next.js 13.x, this issue is fixed in 13.5.9
For Next.js 12.x, this issue is fixed in 12.3.5
For Next.js 11.x, consult the below workaround.
Note: Next.js deployments hosted on Vercel are automatically protected against this vulnerability.
Workaround
If patching to a safe version is infeasible, we recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application.
Summary
We received a responsible disclosure from Allam Rachid (zhero) for a low-severity race-condition vulnerability in Next.js. This issue only affects the Pages Router under certain misconfigurations, causing normal endpoints to serve pageProps data instead of standard HTML.
A low-severity vulnerability in Next.js has been fixed in version 15.2.2. This issue may have allowed limited source code exposure when the dev server was running with the App Router enabled. The vulnerability only affects local development environments and requires the user to visit a malicious webpage while npm run dev is active.
Because the mitigation is potentially a breaking change for some development setups, to opt-in to the fix, you must configure allowedDevOrigins in your next config after upgrading to a patched version. Learn more.
A vulnerability affecting Next.js has been addressed. It impacted versions 15.0.4 through 15.1.8 and involved a cache poisoning bug leading to a Denial of Service (DoS) condition.
Under certain conditions, this issue may allow a HTTP 204 response to be cached for static pages, leading to the 204 response being served to all users attempting to access the page
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. The issue allowed attacker-controlled external image sources to trigger file downloads with arbitrary content and filenames under specific configurations. This behavior could be abused for phishing or malicious file delivery.
All users relying on images.domains or images.remotePatterns are encouraged to upgrade and verify that external image sources are strictly validated.
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. When images returned from API routes vary based on request headers (such as Cookie or Authorization), these responses could be incorrectly cached and served to unauthorized users due to a cache key confusion bug.
All users are encouraged to upgrade if they use API routes to serve images that depend on request headers and have image optimization enabled.
A vulnerability in Next.js Middleware has been fixed in v14.2.32 and v15.4.7. The issue occurred when request headers were directly passed into NextResponse.next(). In self-hosted applications, this could allow Server-Side Request Forgery (SSRF) if certain sensitive headers from the incoming request were reflected back into the response.
All users implementing custom middleware logic in self-hosted environments are strongly encouraged to upgrade and verify correct usage of the next() function.
A vulnerability affects certain React packages1 for versions 19.0.0, 19.1.0, 19.1.1, and 19.2.0 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55182.
The vulnerability also affects experimental canary releases starting with 14.3.0-canary.77. Users on any of the 14.3 canary builds should either downgrade to a 14.x stable release or 14.3.0-canary.76.
All users of stable 15.x or 16.x Next.js versions should upgrade to a patched, stable version immediately.
A vulnerability affects certain React packages for versions 19.0.0, 19.0.1, 19.1.0, 19.1.1, 19.1.2, 19.2.0, and 19.2.1 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55184.
A malicious HTTP request can be crafted and sent to any App Router endpoint that, when deserialized, can cause the server process to hang and consume CPU. This can result in denial of service in unpatched environments.
A vulnerability affects certain React packages for versions 19.0.0, 19.0.1, 19.1.0, 19.1.1, 19.1.2, 19.2.0, and 19.2.1 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55183.
A malicious HTTP request can be crafted and sent to any App Router endpoint that can return the compiled source code of Server Functions. This could reveal business logic, but would not expose secrets unless they were hardcoded directly into Server Function code.
A vulnerability affects certain React Server Components packages for versions 19.0.x, 19.1.x, and 19.2.x and frameworks that use the affected packages, including Next.js 13.x, 14.x, 15.x, and 16.x using the App Router. The issue is tracked upstream as CVE-2026-23864.
A specially crafted HTTP request can be sent to any App Router Server Function endpoint that, when deserialized, may trigger excessive CPU usage, out-of-memory exceptions, or server crashes. This can result in denial of service in unpatched environments.
A DoS vulnerability exists in self-hosted Next.js applications that have remotePatterns configured for the Image Optimizer. The image optimization endpoint (/_next/image) loads external images entirely into memory without enforcing a maximum size limit, allowing an attacker to cause out-of-memory conditions by requesting optimization of arbitrarily large images. This vulnerability requires that remotePatterns is configured to allow image optimization from external domains and that the attacker can serve or control a large image on an allowed domain.
Strongly consider upgrading to 15.5.10 and 16.1.5 to reduce risk and prevent availability issues in Next applications.
When Next.js rewrites proxy traffic to an external backend, a crafted DELETE/OPTIONS request using Transfer-Encoding: chunked could trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes.
Impact
An attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel.
Patches
The vulnerability originated in an upstream library vendored by Next.js. It is fixed by updating that dependency’s behavior so content-length: 0 is added only when both content-length and transfer-encoding are absent, and transfer-encoding is no longer removed in that code path.
Workarounds
If upgrade is not immediately possible:
Block chunked DELETE/OPTIONS requests on rewritten routes at your edge/proxy.
Enforce authentication/authorization on backend routes per our security guidance.
The default Next.js image optimization disk cache (/_next/image) did not have a configurable upper bound, allowing unbounded cache growth.
Impact
An attacker could generate many unique image-optimization variants and exhaust disk space, causing denial of service. Note that this does not impact platforms that have their own image optimization capabilities, such as Vercel.
Patches
Fixed by adding an LRU-backed disk cache with images.maximumDiskCacheSize, including eviction of least-recently-used entries when the limit is exceeded. Setting maximumDiskCacheSize: 0 disables disk caching.
Workarounds
If upgrade is not immediately possible:
Periodically clean .next/cache/images.
Reduce variant cardinality (e.g., tighten values for images.localPatterns, images.remotePatterns, and images.qualities)
A vulnerability affects certain React Server Components packages for versions 19.x and frameworks that use the affected packages, including Next.js 13.x, 14.x, 15.x, and 16.x using the App Router. The issue is tracked upstream as CVE-2026-23869. You can read more about this advisory our this changelog.
A specially crafted HTTP request can be sent to any App Router Server Function endpoint that, when deserialized, may trigger excessive CPU usage. This can result in denial of service in unpatched environments.
Applications using Partial Prerendering through the Cache Components feature can be vulnerable to connection exhaustion through crafted POST requests to a server action. In affected configurations, a malicious request can trigger a request-body handling deadlock that leaves connections open for an extended period, consuming file descriptors and server capacity until legitimate users are denied service.
Fix
We now treat the header used for resuming Partial Prerendered requests as an internal-only header and strip it from untrusted incoming requests. This header should never be accepted directly from external clients.
Workarounds
If you cannot upgrade immediately, block requests that would be handled by Next.js if they contain the Next-Resume header at the edge.
Applications using React Server Components can be vulnerable to cache poisoning when shared caches do not correctly partition response variants. Under affected conditions, an attacker can cause an RSC response to be served from the original URL and poison shared cache entries so later visitors receive component payloads instead of the expected HTML.
Fix
We now validate and interpret RSC request headers consistently across request classification and rendering, and we enforce the intended cache-busting behavior so RSC payloads are not unexpectedly served from the original URL.
Workarounds
If you cannot upgrade immediately, ensure your CDN or reverse proxy keys on the relevant RSC request headers and honors Vary, or disable shared caching for affected App Router and RSC responses.
Self-hosted applications using the built-in Node.js server can be vulnerable to server-side request forgery through crafted WebSocket upgrade requests. An attacker can cause the server to proxy requests to arbitrary internal or external destinations, which may expose internal services or cloud metadata endpoints. Vercel-hosted deployments are not affected.
Fix
We now apply the same safety checks to WebSocket upgrade handling that already existed for normal HTTP requests, so upgrade requests are only proxied when routing has explicitly marked them as safe external rewrites.
Workarounds
If you cannot upgrade immediately, do not expose the origin server directly to untrusted networks. If WebSocket upgrades are not required, block them at your reverse proxy or load balancer, and restrict origin egress to internal networks and metadata services where possible.
App Router applications that rely on CSP nonces can be vulnerable to stored cross-site scripting when deployed behind shared caches. In affected versions, malformed nonce values derived from request headers could be reflected into rendered HTML in an unsafe way, allowing an attacker to poison cached responses and cause script execution for later visitors.
Fix
We now reject or ignore malformed nonce values before they are embedded into HTML and apply stricter nonce sanitization so request-derived nonce data cannot break out of the intended attribute context.
Workarounds
If you cannot upgrade immediately, strip inbound Content-Security-Policy request headers from untrusted traffic.
A vulnerability affects certain React Server Components packages for versions 19.x and frameworks that use the affected packages, including Next.js 13.x, 14.x, 15.x, and 16.x using the App Router. The issue is tracked upstream as CVE-2026-23870.
A specially crafted HTTP request can be sent to any App Router Server Function endpoint that, when deserialized, may trigger excessive CPU usage. This can result in denial of service in unpatched environments.
Applications that use beforeInteractive scripts together with untrusted content can be vulnerable to cross-site scripting. In affected versions, serialized script content was not escaped safely before being embedded into the document, which could allow attacker-controlled input to break out of the intended script context and execute arbitrary JavaScript in a visitor's browser.
Fix
We now HTML-escape serialized beforeInteractive script content before embedding it into the page, preventing attacker-controlled content from breaking out of the inline script boundary.
Workarounds
If you cannot upgrade immediately, do not pass untrusted data into beforeInteractive scripts. If that pattern is unavoidable, sanitize or escape the content before embedding it.
Applications using the Pages Router with i18n configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less /_next/data/<buildId>/<page>.json requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks.
Fix
The matcher logic was updated to perform the same match as it would on a non-i18n data route.
Workarounds
If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Next.js uses the x-nextjs-data request header for internal data requests. On affected versions, an external client could send this header on a normal request to a path handled by middleware that returns a redirect.
When that happened, the middleware/proxy could treat the request as a data request and replace the standard Location redirect header with the internal x-nextjs-redirect header. Browsers do not follow x-nextjs-redirect, so the response became an unusable redirect for normal clients.
If the application was deployed behind a CDN or reverse proxy that caches 3xx responses without varying on this header, a single attacker request could poison the cached redirect response for the affected path. Subsequent visitors could then receive a cached redirect response without a Location header, causing a denial of service for that redirect path until the cache entry expired or was purged.
Affected scenarios
This affects applications that:
use middleware or proxy redirects
are deployed behind a caching CDN or reverse proxy
allow 3xx responses on those paths to be cached without differentiating internal data requests from normal requests
Fix
The fix stops trusting x-nextjs-data by itself for middleware redirect handling. A request is now treated as an internal data request only when it is validated as such by internal routing state, preserving legitimate data-request redirect behavior while preventing external header injection from changing normal redirect responses.
Workarounds
Before upgrading, users can reduce risk by:
configuring the CDN or reverse proxy to vary its cache key on x-nextjs-data for affected responses
When self-hosting Next.js with the default image loader, the Image Optimization API fetches local images entirely into memory without enforcing a maximum size limit. An attacker could cause out-of-memory conditions by requesting large local assets from the /_next/image endpoint that match the images.localPatterns configuration (by default, all patterns are allowed).
If you are using images.localPatterns, only the patterns in that array are impacted.
If you are using images.unoptimized: true, you are NOT impacted.
If you are using images.loader: 'custom', you are NOT impacted.
If you are using Vercel, you are NOT impacted.
Fix
We now apply response size limits consistently to internal image fetches, not just external ones, and fail oversized responses before they can exhaust process memory.
This can be adjusted using the images.maximumResponseBody configuration.
Workarounds
If you cannot upgrade immediately, avoid routing large local assets through /_next/image, disable image optimization for large or untrusted local files, or block image optimization access to those assets at the edge.
You can disable using the images.localPatterns: [] configuration. This will still allow fetching remote images (which is not impacted).
React Server Component responses can be vulnerable to cache poisoning in deployments that rely on shared caches with insufficient response partitioning. In affected conditions, collisions in the _rsc cache-busting value can allow an attacker to poison cache entries so users receive the wrong response variant for a given URL.
Fix
We strengthened the _rsc cache-busting mechanism to make practical collisions significantly harder and to better separate response variants that should not share cache entries.
Workarounds
If you cannot upgrade immediately, ensure intermediary caches correctly honor Vary for RSC-related request headers, or disable shared caching for affected RSC responses until you can deploy a patched release.
Empty release to ensure next@latest points at a stable release. Next.js only allows publishing with Trusted Publishing enabled. In order to fix NPM dist-tags, we have to release a new version. Updating dist-tags is not possible with Trusted Publishing.
Next steps: Take a moment to review the security alert above. Review
the linked package source code to understand the potential risk. Ensure the
package is not malicious before proceeding. If you're unsure how to proceed,
reach out to your security team or ask the Socket team for help at
support@socket.dev.
Suggestion: Packages should not obfuscate their code. Consider not using packages with obfuscated code.
Mark the package as acceptable risk. To ignore this alert only
in this pull request, reply with the comment
@SocketSecurity ignore npm/@emnapi/runtime@1.11.1. You can
also ignore all packages with @SocketSecurity ignore-all.
To ignore an alert for all future pull requests, use Socket's Dashboard to
change the triage state of this alert.
Next steps: Take a moment to review the security alert above. Review
the linked package source code to understand the potential risk. Ensure the
package is not malicious before proceeding. If you're unsure how to proceed,
reach out to your security team or ask the Socket team for help at
support@socket.dev.
Suggestion: Packages should not be running non-essential scripts during install and there are often solutions to problems people solve with install scripts that can be run at publish time instead.
Mark the package as acceptable risk. To ignore this alert only
in this pull request, reply with the comment
@SocketSecurity ignore npm/sharp@0.34.5. You can
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To ignore an alert for all future pull requests, use Socket's Dashboard to
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^15.0.3→^16.0.0Authorization Bypass in Next.js Middleware
CVE-2025-29927 / GHSA-f82v-jwr5-mffw
More information
Details
Impact
It is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware.
Patches
15.2.314.2.25Note: Next.js deployments hosted on Vercel are automatically protected against this vulnerability.
Workaround
If patching to a safe version is infeasible, we recommend that you prevent external user requests which contain the
x-middleware-subrequestheader from reaching your Next.js application.Credits
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js Race Condition to Cache Poisoning
CVE-2025-32421 / GHSA-qpjv-v59x-3qc4
More information
Details
Summary
We received a responsible disclosure from Allam Rachid (zhero) for a low-severity race-condition vulnerability in Next.js. This issue only affects the Pages Router under certain misconfigurations, causing normal endpoints to serve
pagePropsdata instead of standard HTML.Learn more here
Credit
Thank you to Allam Rachid (zhero) for the responsible disclosure. This research was rewarded as part of our bug bounty program.
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Information exposure in Next.js dev server due to lack of origin verification
CVE-2025-48068 / GHSA-3h52-269p-cp9r
More information
Details
Summary
A low-severity vulnerability in Next.js has been fixed in version 15.2.2. This issue may have allowed limited source code exposure when the dev server was running with the App Router enabled. The vulnerability only affects local development environments and requires the user to visit a malicious webpage while
npm run devis active.Because the mitigation is potentially a breaking change for some development setups, to opt-in to the fix, you must configure
allowedDevOriginsin your next config after upgrading to a patched version. Learn more.Learn more: https://vercel.com/changelog/cve-2025-48068
Credit
Thanks to sapphi-red and Radman Siddiki for responsibly disclosing this issue.
Severity
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:L/SI:N/SA:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.JS vulnerability can lead to DoS via cache poisoning
CVE-2025-49826 / GHSA-67rr-84xm-4c7r
More information
Details
Summary
A vulnerability affecting Next.js has been addressed. It impacted versions 15.0.4 through 15.1.8 and involved a cache poisoning bug leading to a Denial of Service (DoS) condition.
Under certain conditions, this issue may allow a HTTP 204 response to be cached for static pages, leading to the 204 response being served to all users attempting to access the page
More details: CVE-2025-49826
Credits
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js Content Injection Vulnerability for Image Optimization
CVE-2025-55173 / GHSA-xv57-4mr9-wg8v
More information
Details
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. The issue allowed attacker-controlled external image sources to trigger file downloads with arbitrary content and filenames under specific configurations. This behavior could be abused for phishing or malicious file delivery.
All users relying on
images.domainsorimages.remotePatternsare encouraged to upgrade and verify that external image sources are strictly validated.More details at Vercel Changelog
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js Affected by Cache Key Confusion for Image Optimization API Routes
CVE-2025-57752 / GHSA-g5qg-72qw-gw5v
More information
Details
A vulnerability in Next.js Image Optimization has been fixed in v15.4.5 and v14.2.31. When images returned from API routes vary based on request headers (such as
CookieorAuthorization), these responses could be incorrectly cached and served to unauthorized users due to a cache key confusion bug.All users are encouraged to upgrade if they use API routes to serve images that depend on request headers and have image optimization enabled.
More details at Vercel Changelog
Severity
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js Improper Middleware Redirect Handling Leads to SSRF
CVE-2025-57822 / GHSA-4342-x723-ch2f
More information
Details
A vulnerability in Next.js Middleware has been fixed in v14.2.32 and v15.4.7. The issue occurred when request headers were directly passed into
NextResponse.next(). In self-hosted applications, this could allow Server-Side Request Forgery (SSRF) if certain sensitive headers from the incoming request were reflected back into the response.All users implementing custom middleware logic in self-hosted environments are strongly encouraged to upgrade and verify correct usage of the
next()function.More details at Vercel Changelog
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js is vulnerable to RCE in React flight protocol
GHSA-9qr9-h5gf-34mp
More information
Details
A vulnerability affects certain React packages1 for versions 19.0.0, 19.1.0, 19.1.1, and 19.2.0 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55182.
Fixed in:
React: 19.0.1, 19.1.2, 19.2.1
Next.js: 15.0.5, 15.1.9, 15.2.6, 15.3.6, 15.4.8, 15.5.7, 16.0.7, 15.6.0-canary.58, 16.1.0-canary.12+
The vulnerability also affects experimental canary releases starting with 14.3.0-canary.77. Users on any of the 14.3 canary builds should either downgrade to a 14.x stable release or 14.3.0-canary.76.
All users of stable 15.x or 16.x Next.js versions should upgrade to a patched, stable version immediately.
1 The affected React packages are:
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next Vulnerable to Denial of Service with Server Components
GHSA-mwv6-3258-q52c
More information
Details
A vulnerability affects certain React packages for versions 19.0.0, 19.0.1, 19.1.0, 19.1.1, 19.1.2, 19.2.0, and 19.2.1 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55184.
A malicious HTTP request can be crafted and sent to any App Router endpoint that, when deserialized, can cause the server process to hang and consume CPU. This can result in denial of service in unpatched environments.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next Server Actions Source Code Exposure
GHSA-w37m-7fhw-fmv9
More information
Details
A vulnerability affects certain React packages for versions 19.0.0, 19.0.1, 19.1.0, 19.1.1, 19.1.2, 19.2.0, and 19.2.1 and frameworks that use the affected packages, including Next.js 15.x and 16.x using the App Router. The issue is tracked upstream as CVE-2025-55183.
A malicious HTTP request can be crafted and sent to any App Router endpoint that can return the compiled source code of Server Functions. This could reveal business logic, but would not expose secrets unless they were hardcoded directly into Server Function code.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js HTTP request deserialization can lead to DoS when using insecure React Server Components
GHSA-h25m-26qc-wcjf
More information
Details
A vulnerability affects certain React Server Components packages for versions 19.0.x, 19.1.x, and 19.2.x and frameworks that use the affected packages, including Next.js 13.x, 14.x, 15.x, and 16.x using the App Router. The issue is tracked upstream as CVE-2026-23864.
A specially crafted HTTP request can be sent to any App Router Server Function endpoint that, when deserialized, may trigger excessive CPU usage, out-of-memory exceptions, or server crashes. This can result in denial of service in unpatched environments.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js self-hosted applications vulnerable to DoS via Image Optimizer remotePatterns configuration
CVE-2025-59471 / GHSA-9g9p-9gw9-jx7f
More information
Details
A DoS vulnerability exists in self-hosted Next.js applications that have
remotePatternsconfigured for the Image Optimizer. The image optimization endpoint (/_next/image) loads external images entirely into memory without enforcing a maximum size limit, allowing an attacker to cause out-of-memory conditions by requesting optimization of arbitrarily large images. This vulnerability requires thatremotePatternsis configured to allow image optimization from external domains and that the attacker can serve or control a large image on an allowed domain.Strongly consider upgrading to 15.5.10 and 16.1.5 to reduce risk and prevent availability issues in Next applications.
Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js: HTTP request smuggling in rewrites
CVE-2026-29057 / GHSA-ggv3-7p47-pfv8
More information
Details
Summary
When Next.js rewrites proxy traffic to an external backend, a crafted
DELETE/OPTIONSrequest usingTransfer-Encoding: chunkedcould trigger request boundary disagreement between the proxy and backend. This could allow request smuggling through rewritten routes.Impact
An attacker could smuggle a second request to unintended backend routes (for example, internal/admin endpoints), bypassing assumptions that only the configured rewrite destination/path is reachable. This does not impact applications hosted on providers that handle rewrites at the CDN level, such as Vercel.
Patches
The vulnerability originated in an upstream library vendored by Next.js. It is fixed by updating that dependency’s behavior so
content-length: 0is added only when bothcontent-lengthandtransfer-encodingare absent, andtransfer-encodingis no longer removed in that code path.Workarounds
If upgrade is not immediately possible:
DELETE/OPTIONSrequests on rewritten routes at your edge/proxy.Severity
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js: Unbounded next/image disk cache growth can exhaust storage
CVE-2026-27980 / GHSA-3x4c-7xq6-9pq8
More information
Details
Summary
The default Next.js image optimization disk cache (
/_next/image) did not have a configurable upper bound, allowing unbounded cache growth.Impact
An attacker could generate many unique image-optimization variants and exhaust disk space, causing denial of service. Note that this does not impact platforms that have their own image optimization capabilities, such as Vercel.
Patches
Fixed by adding an LRU-backed disk cache with
images.maximumDiskCacheSize, including eviction of least-recently-used entries when the limit is exceeded. SettingmaximumDiskCacheSize: 0disables disk caching.Workarounds
If upgrade is not immediately possible:
.next/cache/images.images.localPatterns,images.remotePatterns, andimages.qualities)Severity
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js has a Denial of Service with Server Components
GHSA-q4gf-8mx6-v5v3
More information
Details
A vulnerability affects certain React Server Components packages for versions 19.x and frameworks that use the affected packages, including Next.js 13.x, 14.x, 15.x, and 16.x using the App Router. The issue is tracked upstream as CVE-2026-23869. You can read more about this advisory our this changelog.
A specially crafted HTTP request can be sent to any App Router Server Function endpoint that, when deserialized, may trigger excessive CPU usage. This can result in denial of service in unpatched environments.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js vulnerable to Denial of Service via connection exhaustion in applications using Cache Components
CVE-2026-44579 / GHSA-mg66-mrh9-m8jx
More information
Details
Impact
Applications using Partial Prerendering through the Cache Components feature can be vulnerable to connection exhaustion through crafted POST requests to a server action. In affected configurations, a malicious request can trigger a request-body handling deadlock that leaves connections open for an extended period, consuming file descriptors and server capacity until legitimate users are denied service.
Fix
We now treat the header used for resuming Partial Prerendered requests as an internal-only header and strip it from untrusted incoming requests. This header should never be accepted directly from external clients.
Workarounds
If you cannot upgrade immediately, block requests that would be handled by Next.js if they contain the
Next-Resumeheader at the edge.Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js vulnerable to cache poisoning in React Server Component responses
CVE-2026-44576 / GHSA-wfc6-r584-vfw7
More information
Details
Impact
Applications using React Server Components can be vulnerable to cache poisoning when shared caches do not correctly partition response variants. Under affected conditions, an attacker can cause an RSC response to be served from the original URL and poison shared cache entries so later visitors receive component payloads instead of the expected HTML.
Fix
We now validate and interpret
RSCrequest headers consistently across request classification and rendering, and we enforce the intended cache-busting behavior so RSC payloads are not unexpectedly served from the original URL.Workarounds
If you cannot upgrade immediately, ensure your CDN or reverse proxy keys on the relevant RSC request headers and honors
Vary, or disable shared caching for affected App Router and RSC responses.Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:LReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js vulnerable to server-side request forgery in applications using WebSocket upgrades
CVE-2026-44578 / GHSA-c4j6-fc7j-m34r
More information
Details
Impact
Self-hosted applications using the built-in Node.js server can be vulnerable to server-side request forgery through crafted WebSocket upgrade requests. An attacker can cause the server to proxy requests to arbitrary internal or external destinations, which may expose internal services or cloud metadata endpoints. Vercel-hosted deployments are not affected.
Fix
We now apply the same safety checks to WebSocket upgrade handling that already existed for normal HTTP requests, so upgrade requests are only proxied when routing has explicitly marked them as safe external rewrites.
Workarounds
If you cannot upgrade immediately, do not expose the origin server directly to untrusted networks. If WebSocket upgrades are not required, block them at your reverse proxy or load balancer, and restrict origin egress to internal networks and metadata services where possible.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js vulnerable to cross-site scripting in App Router applications using CSP nonces
CVE-2026-44581 / GHSA-ffhc-5mcf-pf4q
More information
Details
Impact
App Router applications that rely on CSP nonces can be vulnerable to stored cross-site scripting when deployed behind shared caches. In affected versions, malformed nonce values derived from request headers could be reflected into rendered HTML in an unsafe way, allowing an attacker to poison cached responses and cause script execution for later visitors.
Fix
We now reject or ignore malformed nonce values before they are embedded into HTML and apply stricter nonce sanitization so request-derived nonce data cannot break out of the intended attribute context.
Workarounds
If you cannot upgrade immediately, strip inbound
Content-Security-Policyrequest headers from untrusted traffic.Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js Vulnerable to Denial of Service with Server Components
GHSA-8h8q-6873-q5fj
More information
Details
A vulnerability affects certain React Server Components packages for versions 19.x and frameworks that use the affected packages, including Next.js 13.x, 14.x, 15.x, and 16.x using the App Router. The issue is tracked upstream as CVE-2026-23870.
A specially crafted HTTP request can be sent to any App Router Server Function endpoint that, when deserialized, may trigger excessive CPU usage. This can result in denial of service in unpatched environments.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js has cross-site scripting in beforeInteractive scripts with untrusted input
CVE-2026-44580 / GHSA-gx5p-jg67-6x7h
More information
Details
Impact
Applications that use
beforeInteractivescripts together with untrusted content can be vulnerable to cross-site scripting. In affected versions, serialized script content was not escaped safely before being embedded into the document, which could allow attacker-controlled input to break out of the intended script context and execute arbitrary JavaScript in a visitor's browser.Fix
We now HTML-escape serialized
beforeInteractivescript content before embedding it into the page, preventing attacker-controlled content from breaking out of the inline script boundary.Workarounds
If you cannot upgrade immediately, do not pass untrusted data into
beforeInteractivescripts. If that pattern is unavoidable, sanitize or escape the content before embedding it.Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js has a Middleware / Proxy bypass in Pages Router applications using i18n
CVE-2026-44573 / GHSA-36qx-fr4f-26g5
More information
Details
Impact
Applications using the Pages Router with
i18nconfigured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less/_next/data/<buildId>/<page>.jsonrequests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks.Fix
The matcher logic was updated to perform the same match as it would on a non-i18n data route.
Workarounds
If you cannot upgrade immediately, enforce authorization in the page's server-side data path instead of relying solely on middleware.
Severity
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js's Middleware / Proxy redirects can be cache-poisoned
CVE-2026-44572 / GHSA-3g8h-86w9-wvmq
More information
Details
Impact
Next.js uses the
x-nextjs-datarequest header for internal data requests. On affected versions, an external client could send this header on a normal request to a path handled by middleware that returns a redirect.When that happened, the middleware/proxy could treat the request as a data request and replace the standard
Locationredirect header with the internalx-nextjs-redirectheader. Browsers do not followx-nextjs-redirect, so the response became an unusable redirect for normal clients.If the application was deployed behind a CDN or reverse proxy that caches 3xx responses without varying on this header, a single attacker request could poison the cached redirect response for the affected path. Subsequent visitors could then receive a cached redirect response without a
Locationheader, causing a denial of service for that redirect path until the cache entry expired or was purged.Affected scenarios
This affects applications that:
Fix
The fix stops trusting
x-nextjs-databy itself for middleware redirect handling. A request is now treated as an internal data request only when it is validated as such by internal routing state, preserving legitimate data-request redirect behavior while preventing external header injection from changing normal redirect responses.Workarounds
Before upgrading, users can reduce risk by:
x-nextjs-datafor affected responsesSeverity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:LReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js has a Denial of Service in the Image Optimization API
CVE-2026-44577 / GHSA-h64f-5h5j-jqjh
More information
Details
Impact
When self-hosting Next.js with the default image loader, the Image Optimization API fetches local images entirely into memory without enforcing a maximum size limit. An attacker could cause out-of-memory conditions by requesting large local assets from the
/_next/imageendpoint that match theimages.localPatternsconfiguration (by default, all patterns are allowed).images.localPatterns, only the patterns in that array are impacted.images.unoptimized: true, you are NOT impacted.images.loader: 'custom', you are NOT impacted.Fix
We now apply response size limits consistently to internal image fetches, not just external ones, and fail oversized responses before they can exhaust process memory.
This can be adjusted using the
images.maximumResponseBodyconfiguration.Workarounds
If you cannot upgrade immediately, avoid routing large local assets through
/_next/image, disable image optimization for large or untrusted local files, or block image optimization access to those assets at the edge.You can disable using the
images.localPatterns: []configuration. This will still allow fetching remote images (which is not impacted).Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Next.js vulnerable to cache poisoning via collisions in React Server Component cache-busting
CVE-2026-44582 / GHSA-vfv6-92ff-j949
More information
Details
Impact
React Server Component responses can be vulnerable to cache poisoning in deployments that rely on shared caches with insufficient response partitioning. In affected conditions, collisions in the
_rsccache-busting value can allow an attacker to poison cache entries so users receive the wrong response variant for a given URL.Fix
We strengthened the
_rsccache-busting mechanism to make practical collisions significantly harder and to better separate response variants that should not share cache entries.Workarounds
If you cannot upgrade immediately, ensure intermediary caches correctly honor
Varyfor RSC-related request headers, or disable shared caching for affected RSC responses until you can deploy a patched release.Severity
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NReferences
This data is provided by the GitHub Advisory Database (CC-BY 4.0).
Release Notes
vercel/next.js (next)
v16.2.10Compare Source
v16.2.9Compare Source
Empty release to ensure
next@latestpoints at a stable release. Next.js only allows publishing with Trusted Publishing enabled. In order to fix NPM dist-tags, we have to release a new version. Updating dist-tags is not possible with Trusted Publishing.v16.2.8Compare Source
Release with no changes in an attempt to fix
next@latestpointing at a prerelease version.v16.2.7Compare Source
Core Changes
playwright-coreto resolve_finishedPromiseonrequestFailed(#93920)router.querycorruption withbasePath+rewrites(#93917)FormDataentries (#94240)Credits
Huge thanks to @eps1lon, @icyJoseph, @unstubbable, @mischnic, @bgw, @timneutkens, and @lukesandberg for helping!
v16.2.6Compare Source
Configuration
📅 Schedule: (UTC)
🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.
♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.
🔕 Ignore: Close this PR and you won't be reminded about this update again.
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