GitLab EE <19.3.1: Missing Namespace Validation Enables Auth User Assignment
CVE-2026-4398 Published on August 27, 2026
Authorization Bypass Through User-Controlled Key in GitLab
GitLab has remediated an issue in GitLab EE affecting all versions from 18.3 before 19.1.7, 19.2 before 19.2.5, and 19.3 before 19.3.1 that, under certain conditions, an authenticated user could have assigned compliance frameworks from namespaces they were not authorized to access to their own project, due to missing namespace validation on self-managed instances.
Vulnerability Analysis
CVE-2026-4398 is exploitable with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
What is an Insecure Direct Object Reference / IDOR Vulnerability?
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
CVE-2026-4398 has been classified to as an Insecure Direct Object Reference / IDOR vulnerability or weakness.
Products Associated with CVE-2026-4398
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Affected Versions
GitLab:- Version 18.3 and below 19.1.7 is affected.
- Version 19.2 and below 19.2.5 is affected.
- Version 19.3 and below 19.3.1 is affected.