Vulnerability · Published Oct 21, 2026 · Assigned by GitLab

CVE-2026-16255Incorrect Authorization in GitLab

Medium 5.9

In plain English

A medium-severity incorrect authorization in GitLab from GitLab. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities).

Severity (CVSS 3.1)5.9Medium

Exploit odds (30 days)0.3%top 82.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
GitLab	GitLab	12.0 – before 19.3.619.4 – before 19.4.319.5 – before 19.5.1

Weakness: CWE-863 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N

References

https://gitlab.com/gitlab-org/gitlab/-/work_items/606479
HackerOne Bug Bounty Report #3809350 technical-description, exploit, permissions-required
https://docs.gitlab.com/releases/patches/patch-release-gitlab-19-5-1-released/