CVE-2026-14288 Overview
CVE-2026-14288 is an improper access control vulnerability in GitLab Enterprise Edition (EE). The flaw affects all versions from 17.4 before 19.3.6, 19.4 before 19.4.3, and 19.5 before 19.5.1. Under certain conditions, an authenticated user could bypass a required merge request approval policy on a protected branch. The weakness exists in how GitLab synchronizes approval rules, categorized under [CWE-706] Use of Incorrectly-Resolved Name or Reference.
Critical Impact
An authenticated user can bypass required merge request approval policies on protected branches, undermining code review controls and introducing unreviewed changes into protected codebases.
Affected Products
- GitLab EE versions 17.4 through 19.3.5
- GitLab EE versions 19.4 through 19.4.2
- GitLab EE version 19.5.0
Discovery Timeline
- 2026-10-22 - CVE-2026-14288 published to the National Vulnerability Database (NVD)
- 2026-10-22 - Last updated in NVD database
Technical Details for CVE-2026-14288
Vulnerability Analysis
The vulnerability resides in GitLab EE's merge request approval policy enforcement for protected branches. Approval policies are intended to require designated reviewers before changes can be merged into protected branches. GitLab synchronizes approval rules when policies, groups, or project configurations change. During this synchronization process, access control checks are not applied consistently. An authenticated user with low-privilege access to the affected project can exploit this gap to bypass approval requirements and merge changes without the mandated reviews.
Root Cause
The root cause is improper access control during approval rule synchronization. When approval rules are reconciled between policy sources and project-level configurations, GitLab fails to properly validate the authorization context of the triggering user or action. This allows the resulting rule state to omit or weaken required approvals that should have been enforced on a protected branch.
Attack Vector
Exploitation requires network access to the GitLab instance and valid authenticated credentials. The attacker must have sufficient project membership to trigger the conditions that cause approval rule synchronization. No user interaction is required beyond the attacker's own actions. Technical details are limited to the published advisory and HackerOne report. See the GitLab Release Patch Note, the GitLab Work Item Details, and HackerOne Report #3797008 for additional context.
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Stop Identity AttacksDetection Methods for CVE-2026-14288
Indicators of Compromise
- Merge requests merged into protected branches without the required number of approvals recorded in the audit log.
- Unexpected modifications or disablement of approval rules on projects governed by merge request approval policies.
- Audit events showing approval rule synchronization activity followed closely by merges that bypass policy constraints.
Detection Strategies
- Review GitLab audit events for merge request activity on protected branches and reconcile against the approval policies that should have applied.
- Compare project-level approval rule configurations against the parent security policy project to identify drift introduced by faulty synchronization.
- Monitor the GitLab REST and GraphQL APIs for calls that modify approval rules or merge requests from accounts without expected privileges.
Monitoring Recommendations
- Enable and centralize GitLab audit event logging and forward it to a SIEM for correlation with code change activity.
- Alert on any merge to a protected branch where the recorded approver count is lower than the policy-defined minimum.
- Track upgrade status across all self-managed GitLab EE instances to confirm remediation of CVE-2026-14288.
How to Mitigate CVE-2026-14288
Immediate Actions Required
- Upgrade self-managed GitLab EE instances to version 19.3.6, 19.4.3, 19.5.1, or later as applicable to your release line.
- Audit recent merges into protected branches governed by approval policies and validate they met the required approval count.
- Rotate or review permissions for accounts that interacted with approval policy configurations during the affected window.
Patch Information
GitLab addressed the issue in versions 19.3.6, 19.4.3, and 19.5.1. GitLab.com is already running the patched release. Details are available in the GitLab Release Patch Note.
Workarounds
- No official workaround has been published; upgrading to a fixed version is the supported remediation path.
- As a compensating control, restrict project membership and reduce the number of users who can trigger approval rule synchronization until patches are applied.
- Enforce additional out-of-band code review for protected branches during the remediation window.
# Verify installed GitLab version on a self-managed instance
sudo gitlab-rake gitlab:env:info | grep -i version
# Upgrade example on Debian/Ubuntu (adjust package version to a fixed release)
sudo apt-get update
sudo apt-get install gitlab-ee=19.5.1-ee.0
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
