CVE-2025-5121: GitLab Auth Bypass Vulnerability

CVE-2025-5121 Overview

A missing authorization check vulnerability has been discovered in GitLab CE/EE that affects all versions from 17.11 before 17.11.4 and 18.0 before 18.0.2. This security flaw allows compliance frameworks to be applied to projects outside the compliance framework's designated group, potentially enabling unauthorized users to manipulate compliance settings across organizational boundaries.

Critical Impact

This authorization bypass vulnerability could allow attackers with low privileges to apply compliance frameworks to projects outside their authorized scope, potentially disrupting organizational compliance policies and gaining unauthorized control over project governance settings.

Affected Products

• GitLab Community Edition (CE) versions 17.11 before 17.11.4
• GitLab Enterprise Edition (EE) versions 17.11 before 17.11.4
• GitLab Community Edition (CE) versions 18.0 before 18.0.2
• GitLab Enterprise Edition (EE) versions 18.0 before 18.0.2

Discovery Timeline

• 2025-06-20 - CVE-2025-5121 published to NVD
• 2025-08-12 - Last updated in NVD database

Technical Details for CVE-2025-5121

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization), indicating that the application fails to perform proper authorization checks when compliance frameworks are being applied to projects. The flaw exists in the compliance framework assignment functionality within GitLab, where the system does not adequately verify whether the user has the appropriate permissions to apply a compliance framework to a specific project.

The vulnerability is network-accessible and requires only low-level privileges to exploit. Notably, it has a changed scope impact, meaning successful exploitation can affect resources beyond the vulnerable component's security scope. This allows an authenticated attacker to potentially impact confidentiality, integrity, and availability of resources outside their normal access boundaries.

Root Cause

The root cause of this vulnerability is a missing authorization check in the compliance framework assignment logic. When a user attempts to apply a compliance framework to a project, the application fails to verify that the project belongs to the same group as the compliance framework. This architectural oversight allows users to bypass intended access controls and apply compliance settings to projects they should not have governance authority over.

Attack Vector

The attack vector for CVE-2025-5121 is network-based, requiring an authenticated user with low privileges. An attacker would need valid GitLab credentials to exploit this vulnerability. The attack does not require user interaction and can be performed programmatically through GitLab's API or web interface.

The exploitation scenario involves an authenticated attacker identifying compliance frameworks they have access to, then attempting to apply these frameworks to projects in different groups where they should not have administrative authority. Due to the missing authorization check, the system processes these requests without validating the cross-group boundary restriction.

For detailed technical information about this vulnerability, refer to the GitLab Issue #545429 and the HackerOne Report #3153908.

Detection Methods for CVE-2025-5121

Indicators of Compromise

• Unexpected compliance framework assignments appearing on projects that are outside the framework's designated group
• Audit logs showing compliance framework modifications by users who lack administrative permissions for the affected projects
• Multiple compliance framework assignment requests from a single user targeting projects across different groups

Detection Strategies

• Review GitLab audit logs for compliance framework assignment events targeting projects outside the framework's group hierarchy
• Monitor API calls to compliance framework endpoints for patterns indicating cross-group assignment attempts
• Implement alerting on unusual compliance framework modification activity, particularly from users with limited group memberships

Monitoring Recommendations

• Enable comprehensive audit logging for all compliance framework operations in GitLab
• Set up alerts for compliance framework changes on sensitive or critical projects
• Regularly audit compliance framework assignments to ensure they align with expected group boundaries

How to Mitigate CVE-2025-5121

Immediate Actions Required

• Upgrade GitLab CE/EE to version 17.11.4 or later for the 17.11.x branch
• Upgrade GitLab CE/EE to version 18.0.2 or later for the 18.0.x branch
• Audit existing compliance framework assignments to identify any unauthorized cross-group applications
• Review audit logs for evidence of exploitation prior to patching

Patch Information

GitLab has addressed this vulnerability in versions 17.11.4 and 18.0.2. Organizations running affected versions should upgrade immediately to receive the security fix that adds proper authorization checks to the compliance framework assignment functionality. Refer to the GitLab Issue #545429 for additional patch details.

Workarounds

• Restrict compliance framework creation and modification permissions to a minimal set of trusted administrators
• Implement network segmentation to limit access to GitLab administrative interfaces
• Monitor and alert on all compliance framework modifications until patching can be completed
• Consider temporarily disabling compliance framework features if they are not critical to operations

# Check current GitLab version
gitlab-rake gitlab:env:info

# Upgrade GitLab to patched version (example for Omnibus installation)
sudo apt-get update && sudo apt-get install gitlab-ce=17.11.4-ce.0
# or for Enterprise Edition
sudo apt-get update && sudo apt-get install gitlab-ee=17.11.4-ee.0