CVE-2025-8770 Overview
CVE-2025-8770 is a business logic vulnerability in GitLab Enterprise Edition (EE) that allows authenticated users to bypass merge request approval policies. The flaw stems from insecure handling of approval rule identifiers, classified under [CWE-639] Authorization Bypass Through User-Controlled Key. Attackers with specific project access can manipulate identifiers to circumvent required approvals and merge unauthorized changes into protected branches. The vulnerability affects GitLab EE versions 18.0 through 18.2.1 and undermines code review governance controls used by enterprises to enforce security and compliance policies.
Critical Impact
Authenticated users can bypass merge request approval policies, allowing unauthorized code changes to reach protected branches without required reviewer sign-off.
Affected Products
- GitLab Enterprise Edition 18.0 prior to 18.0.6
- GitLab Enterprise Edition 18.1 prior to 18.1.4
- GitLab Enterprise Edition 18.2 prior to 18.2.2
Discovery Timeline
- 2025-08-13 - CVE-2025-8770 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-8770
Vulnerability Analysis
The vulnerability resides in the merge request approval policy enforcement logic within GitLab EE. Approval policies define reviewer requirements that must be satisfied before merge requests can be integrated into target branches. The enforcement code references approval rules by identifier without confirming that the referenced rule genuinely applies to the requesting user's context.
An authenticated user with project access can manipulate approval rule identifiers submitted through the API or web interface. By substituting identifiers that resolve to less restrictive rules, the attacker satisfies approval checks without meeting the intended policy requirements. This allows the merge request to proceed as if all required approvers had signed off.
The impact is limited to integrity, with confidentiality and availability unaffected. However, in software supply chain contexts, integrity failures in code review workflows can introduce malicious commits, unreviewed dependency changes, or bypasses of compliance-mandated controls.
Root Cause
The root cause is an Insecure Direct Object Reference [CWE-639] in the approval rule resolution logic. GitLab EE trusts client-supplied approval rule identifiers without validating that the identifier corresponds to a rule the user is authorized to satisfy within the merge request's policy scope.
Attack Vector
Exploitation requires network access to the GitLab instance and low-privileged authenticated access with permission to interact with merge requests. No user interaction is required. The attacker crafts API requests that reference manipulated approval rule identifiers during the merge approval workflow. Successful exploitation results in a merge proceeding without satisfying the actual approval policy, bypassing reviewer requirements and branch protection controls tied to those policies.
See the GitLab Issue #549105 for additional technical context.
Detection Methods for CVE-2025-8770
Indicators of Compromise
- Merge requests marked as approved without corresponding entries in the approval audit log matching the configured policy reviewers.
- API requests to merge request approval endpoints containing approval rule identifiers that do not belong to the target merge request or project scope.
- Merges into protected branches completed by users who would not normally satisfy approval quorum for those branches.
Detection Strategies
- Audit GitLab merge event logs and compare merged changes against configured approval policy requirements to identify discrepancies.
- Correlate approval rule identifiers referenced in API traffic against the project's actual configured approval rules.
- Review recent merges into protected branches for the affected version window and flag any that bypassed expected reviewer sets.
Monitoring Recommendations
- Enable and forward GitLab audit events, including merge request and approval activity, to a centralized logging platform for retention and analysis.
- Alert on merge request approvals completed within short intervals following rule identifier modifications.
- Track and baseline approval workflows per project to detect deviations from established reviewer patterns.
How to Mitigate CVE-2025-8770
Immediate Actions Required
- Upgrade GitLab EE to version 18.0.6, 18.1.4, or 18.2.2 or later, depending on the deployed release branch.
- Audit merge requests completed since the affected versions were deployed to identify potential policy bypasses.
- Rotate or re-review any merges into protected branches that cannot be confirmed as compliant with approval policies.
Patch Information
GitLab has released fixed versions in the 18.0.6, 18.1.4, and 18.2.2 releases. Administrators of self-managed GitLab EE instances should upgrade to the appropriate patched release for their branch. GitLab.com is maintained by GitLab and is already running patched code. Refer to GitLab Issue #549105 for the vendor tracking record.
Workarounds
- No official workaround has been published; upgrading to a fixed version is the required remediation path.
- Where immediate patching is not feasible, restrict merge and push permissions on protected branches to a minimal, trusted set of maintainers and require out-of-band review confirmation.
- Increase audit logging retention and manual review cadence for merge activity on sensitive projects until the upgrade is completed.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
