Auth bypass in GitLab
CVE-2026-16255
GitLab has remediated an issue in GitLab EE affecting all versions from 12.0 before 19.3.6, 19.4 before 19.4.3, and 19.5 before 19.5.1 that, when the instance-wide SAML or LDAP membership lock was enabled, an authenticated user could have granted or accepted project and group membership outside the identity provider's control, due to incomplete enforcement of the membership lock on requests created before the lock was enabled.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- gitlab.com/gitlab-org/gitlab/-/work_items/606479
- hackerone.com/reports/3809350 (technical-description, permissions-required, exploit)
- docs.gitlab.com/releases/patches/patch-release-gitlab-19-5-1-released/
Frequently asked questions
- What is CVE-2026-16255?
- CVE-2026-16255 is a medium-severity vulnerability in GitLab, classified under Incorrect Authorization. CVSS score: 5.9/10. Published 2026-10-22.
- How severe is CVE-2026-16255?
- Medium severity. CVSS v3 base score is 5.9 out of 10.