Overview
CVE-2025-6171 describes a medium severity information disclosure vulnerability affecting GitLab Community Edition (CE) and Enterprise Edition (EE). This vulnerability allows an authenticated attacker with the ‘reporter’ role to potentially view branch names and pipeline details through the packages API endpoint, even when repository access has been explicitly disabled. The vulnerability impacts GitLab versions from 13.2 before 18.3.6, 18.4 before 18.4.4, and 18.5 before 18.5.2. Immediate patching is highly recommended.
Technical Details
The vulnerability stems from insufficient access control checks within the GitLab packages API endpoint. Even when repository access is disabled for a ‘reporter’ role, the API allowed access to certain metadata like branch names and pipeline details. An attacker with reporter privileges could exploit this oversight to enumerate branch names and glean sensitive information about pipeline configurations and execution. This information could then be used to aid in further reconnaissance or potentially identify weaknesses in the codebase or build process.
The specific issue was located within the handling of requests to the packages API in combination with repository access restrictions. A flaw in the authorization logic failed to properly restrict access to branch and pipeline metadata for users with the reporter role.
CVSS Analysis
The vulnerability has been assigned a CVSS score of 5.3 (Medium). This score reflects the following factors:
- Attack Vector (AV): Network (N) – The vulnerability is exploitable over the network.
- Attack Complexity (AC): Low (L) – Exploitation requires little specialized knowledge or access conditions.
- Privileges Required (PR): Low (L) – An attacker requires only the privileges granted to a ‘reporter’ role.
- User Interaction (UI): None (N) – No user interaction is required to exploit the vulnerability.
- Scope (S): Unchanged (U) – An exploitation of this vulnerability will affect only the vulnerable component.
- Confidentiality Impact (C): Low (L) – Limited information disclosure (branch names, pipeline details).
- Integrity Impact (I): None (N) – No impact on data integrity.
- Availability Impact (A): None (N) – No impact on system availability.
Although the impact is primarily limited to information disclosure, the ease of exploitation and the potential for reconnaissance warrants prompt remediation.
Possible Impact
The successful exploitation of CVE-2025-6171 could lead to the following:
- Information Disclosure: Leakage of sensitive information such as branch names and pipeline configurations.
- Reconnaissance: Enabling attackers to gain a deeper understanding of the project’s codebase structure, development practices, and potential attack surfaces.
- Attack Surface Expansion: Potentially identifying vulnerabilities in branches or pipelines through revealed configurations.
While not directly leading to system compromise, the gathered information can be crucial for attackers in planning subsequent attacks.
Mitigation/Patch Steps
To mitigate this vulnerability, it is strongly recommended to upgrade your GitLab instance to one of the following patched versions:
- Upgrade to version 18.3.6 or later (if you are on the 18.3 series).
- Upgrade to version 18.4.4 or later (if you are on the 18.4 series).
- Upgrade to version 18.5.2 or later (if you are on the 18.5 series).
Follow the official GitLab upgrade documentation for detailed instructions on how to upgrade your instance. Regularly check for security updates and apply them promptly to minimize your exposure to potential vulnerabilities.
