CVE-2026-3176: GitLab EE Auth Bypass Vulnerability

CVE-2026-3176 Overview

CVE-2026-3176 is an authorization flaw in GitLab Enterprise Edition (EE) that allows authenticated users with limited permissions to access project information they should not see. The issue stems from insufficient authorization checks in affected versions and is tracked under [CWE-862: Missing Authorization]. GitLab has issued patches across the 18.x and 19.x release lines. The vulnerability requires authentication and elevated attack complexity, limiting practical exploitation. It impacts confidentiality but does not affect integrity or availability of the platform.

Critical Impact
An authenticated low-privilege user can read project information they were not authorized to view, leading to unauthorized disclosure of source code metadata, configuration, or internal project details.

Affected Products

GitLab EE versions 18.6 through versions prior to 18.11.6
GitLab EE versions 19.0 through versions prior to 19.0.3
GitLab EE versions 19.1 through versions prior to 19.1.1

Discovery Timeline

2026-06-25 - CVE-2026-3176 published to NVD
2026-06-25 - Last updated in NVD database
Reported via HackerOne Report #3568164
Patched in GitLab Patch Release 19.1.1

Technical Details for CVE-2026-3176

Vulnerability Analysis

The vulnerability is a broken access control issue in GitLab EE. Under specific conditions, GitLab failed to enforce authorization checks when an authenticated user requested project information. A user holding limited permissions on a GitLab instance could leverage these gaps to retrieve project data outside their permitted scope.

The weakness maps to [CWE-862: Missing Authorization]. The application performed the requested action without verifying that the requester possessed the privileges required to view the targeted resource. Because the attack vector is the network and authentication is required, the issue primarily concerns multi-tenant GitLab EE deployments where users share an instance but should be isolated by project membership and role.

The defect affects confidentiality only. Attackers cannot modify project content or disrupt service availability through this flaw alone. However, disclosed project metadata can support reconnaissance for follow-on attacks against the development pipeline.

Root Cause

The root cause is an incomplete authorization check on a project information code path. The handler accepted requests from authenticated users without validating that the user's role granted access to the targeted project resource. See GitLab Work Item 591373 for the upstream tracking issue.

Attack Vector

An authenticated user with a low-privilege account on the GitLab EE instance issues network requests to project information endpoints. Exploitation requires specific preconditions on the target environment, reflected in the high attack complexity rating. No user interaction is required from the victim. Successful requests return project data the user should not be authorized to read.

Detection Methods for CVE-2026-3176

Indicators of Compromise

Audit log entries showing low-privilege accounts accessing projects where they hold no explicit membership or role assignment.
Spikes in API requests from a single authenticated user enumerating project IDs or project information endpoints.
Access patterns that bypass expected role boundaries on private or internal projects.

Detection Strategies

Review GitLab audit events for project_access and project read operations correlated against the requesting user's role assignments.
Compare API access logs against project membership tables to flag reads by non-members.
Hunt for sequential access to many project resources by a single non-administrator account within a short timeframe.

Monitoring Recommendations

Forward GitLab audit logs and Rails production logs to a centralized logging platform for retention and correlation.
Alert on unusual project information API access from users with Guest or Reporter roles.
Track usage of project-related GraphQL and REST endpoints by user identity to baseline normal behavior.

How to Mitigate CVE-2026-3176

Immediate Actions Required

Upgrade GitLab EE to version 18.11.6, 19.0.3, or 19.1.1 or later, depending on your current release line.
Inventory all self-managed GitLab EE instances and verify their version against the patched releases.
Review audit logs for suspicious project access by low-privilege accounts during the exposure window.

Patch Information

GitLab released fixed versions 18.11.6, 19.0.3, and 19.1.1 that add the missing authorization checks. Refer to the GitLab Patch Release 19.1.1 advisory for upgrade instructions and full release notes. GitLab.com SaaS instances are patched by the vendor.

Workarounds

No vendor-supplied workaround is documented. Apply the patched release.
Restrict instance access to trusted users where feasible until the upgrade is complete.
Tighten project visibility settings and review role assignments to reduce the pool of accounts that could exploit the flaw.

bash

# Verify the installed GitLab version after upgrade
sudo gitlab-rake gitlab:env:info | grep -i version

# Example upgrade on Omnibus (Debian/Ubuntu) - adjust to your target patched version
sudo apt-get update
sudo apt-get install gitlab-ee=19.1.1-ee.0