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SeaweedFS: Unauthenticated SSRF with response read-back via VolumeServer.FetchAndWriteNeedle

Critical severity GitHub Reviewed Published Jul 8, 2026 in seaweedfs/seaweedfs • Updated Aug 11, 2026

Package

gomod github.com/seaweedfs/seaweedfs (Go)

Affected versions

< 0.0.0-20260512171120-69da20bdaec9

Patched versions

0.0.0-20260512171120-69da20bdaec9

Description

Impact

VolumeServer.FetchAndWriteNeedle fetches a caller-supplied remote endpoint and writes the response into a needle. Before 4.24 this RPC performed no authentication and no validation of the target, so anyone able to reach a volume server's gRPC port could coerce the server into issuing requests to arbitrary hosts — including loopback, link-local, RFC 1918, and cloud metadata endpoints such as 169.254.169.254 — and read the response back. On cloud deployments this discloses instance metadata and IAM credentials, and can be used to reach otherwise-unexposed internal services (SSRF with response read-back).

The volume server gRPC plane is unauthenticated on a default deployment, so no credentials are required. Configuring the documented JWT signing keys does not close it, because that hardening does not apply to this RPC.

Affected component

  • weed/server/volume_grpc_remote.go (FetchAndWriteNeedle)
  • weed/remote_storage/s3/s3_storage_client.go

Patches

Fixed in 4.24. FetchAndWriteNeedle now requires admin authorization and refuses loopback / link-local / RFC 1918 / IMDS destinations through a guarded dialer that resolves the host itself and pins the resolved address for the duration of the request, defeating DNS-rebinding. The Rust volume server carries the equivalent endpoint validation.

Workarounds

Restrict volume server gRPC ports to trusted hosts via firewall / network policy, and enable mTLS via security.toml.

References

@chrislusf chrislusf published to seaweedfs/seaweedfs Jul 8, 2026
Published to the GitHub Advisory Database Aug 11, 2026
Reviewed Aug 11, 2026
Last updated Aug 11, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

EPSS score

Weaknesses

Server-Side Request Forgery (SSRF)

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. Learn more on MITRE.

CVE ID

CVE-2026-73080

GHSA ID

GHSA-87fv-vqqr-m4jr

Source code

Credits

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