What’s Vulnerable › Vulnerabilities

CVE-2026-16255: Incorrect Authorization in GitLab

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-21 · updated 2026-10-30
• Weakness: CWE-863

Description

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.

Affected products

• GitLab: from 12.0.0 before 19.3.6; from 19.4.0 before 19.4.3; 19.5.0 (and their updates) — fixed in 19.3.6, 19.4.3
• GitLab: from 12.0 before 19.3.6; from 19.4 before 19.4.3; from 19.5 before 19.5.1 — fixed in 19.3.6, 19.4.3, 19.5.1

How to fix

Upgrade to a fixed version: GitLab 19.3.6, 19.4.3; GitLab 19.3.6, 19.4.3, 19.5.1. Check the vendor advisory for mitigations.

References

• https://docs.gitlab.com/releases/patches/patch-release-gitlab-19-5-1-released/
• https://gitlab.com/gitlab-org/gitlab/-/work_items/606479
• https://hackerone.com/reports/3809350

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