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Craft CMS Vulnerable to Privilege Escalation/Bypass through UsersController->actionImpersonateWithToken()

Critical severity GitHub Reviewed Published Mar 16, 2026 in craftcms/cms • Updated Mar 16, 2026

Package

composer craftcms/cms (Composer)

Affected versions

>= 4.0.0-RC1, <= 4.17.5
>= 5.0.0-RC1, <= 5.9.11

Patched versions

4.17.6
5.9.12

Description

Summary

A low-privilege user (or an unauthenticated user who has been sent a shared URL) can escalate their privileges to admin by abusing UsersController->actionImpersonateWithToken.

Affected users should update to Craft 4.17.6 and 5.9.12 to mitigate the issue.

Details

This vulnerability allows any low-privilege user to escalate their privileges and become an admin, or, in extreme circumstances, unprivileged users to do the same.

Therefore, this vulnerability affects Craft Pro and Team more than Craft Solo.

Specifically, an attacker who possesses a valid “preview token” can then append &action=users/impersonate-with-token&userId=1&prevUserId=1 to the preview URL to hijack the request into the impersonation endpoint, logging in as any user (including admin) without authentication. Getting the preview token is easy, and all an editor would have to do is create a single article, click “Preview”, and then recover this token.

Here’s what happens:

  1. The action re-dispatch in actionPreview() passes $skipSpecialHandling=true to handleRequest(), bypassing all security guards, and passes $checkToken=false to checkIfActionRequest(), which allows an attacker-controlled action query parameter to override the dispatch target.
  2. The requireToken() guard on actionImpersonateWithToken() only checks a boolean (_hadToken) that was set when the preview token was initially resolved. It does not verify that the token was intended for the impersonation action, and so any valid token from any route satisfies the check.
  3. actionImpersonateWithToken is listed in $allowAnonymous and performs no authorization beyond requireToken(), so no prior authentication is required.

PoC

The PoC achieves full admin takeover on the latest Craft CMS 5.9.10. Spawn a local version of Craft. Then, you’ll want to log in and create a valid setup:

  1. Log in at http://host:18895/admin
  2. Go to Settings,  Sections, New Section (name: "Blog", type: "Channel")
  3. Under Site Settings, set URI Format to blog/{slug}
  4. Then go to Entries, New Entry, Blog, and give it any title

Next, obtain a preview token

  1. Open the saved entry in the editor
  2. Click the Preview button
  3. A preview pane opens with the entry rendered in an iframe
  4. Right-click inside the preview pane and Inspect Element
  5. Find the <iframe> element; its src contains the tokenized URL: http://host:18895/blog/title?x-craft-live-preview=...&token=XXXXXXXX
  6. Copy the token= value

Finally, execute the exploit:

  1. Open a new incognito/private browser window
  2. Navigate to: http://host:18895/?token=XXXXXXXX&action=users/impersonate-with-token&userId=1&prevUserId=1
  3. You may see a 404. This is expected.

To verify the exploit, in the same incognito tab, navigate to http://host:18895/admin. You should land on the admin dashboard, logged in as admin, without ever entering credentials.

Impact

Privilege escalation; everyone is impacted.

References

@angrybrad angrybrad published to craftcms/cms Mar 16, 2026
Published to the GitHub Advisory Database Mar 16, 2026
Reviewed Mar 16, 2026
Published by the National Vulnerability Database Mar 16, 2026
Last updated Mar 16, 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 v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements Present
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity High
Availability High
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

EPSS score

Weaknesses

Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. Learn more on MITRE.

CVE ID

CVE-2026-32267

GHSA ID

GHSA-cc7p-2j3x-x7xf

Source code

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