---
id: "CVE-2026-16255"
kind: "vulnerability"
aliases: ["CVE-2026-16255"]
title: "GitLab EE: stale requests bypass SAML or LDAP membership lock"
severity: "medium"
cvss: 5.9
epss: 0.00209
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["gitlab", "ldap", "package", "saml", "self-hosted"]
not_affected_if: ["default-config", "gitlab-ce"]
published_at: "2026-10-22T01:16:59+00:00"
first_seen_at: "2026-10-23T21:57:30+00:00"
updated_at: "2026-10-25T04:08:01+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-16255", "first_seen_at": "2026-10-23T21:57:30+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-16255", "first_seen_at": "2026-10-24T07:15:52+00:00"}]
---

# GitLab EE: stale requests bypass SAML or LDAP membership lock

When the instance-wide SAML or LDAP membership lock is enabled, requests created before the lock was turned on can still grant or accept project and group membership outside the identity provider's control. An authenticated user can use this to gain access to projects and groups they should not be able to join.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the GitLab version with `gitlab-rake gitlab:env:info` or the admin Version page; affected if below `19.3.6`, between `19.4` and `19.4.2`, or between `19.5` and `19.5.0` on EE installs
- Check whether the instance-wide SAML or LDAP membership lock is enabled in the Admin Area settings

## Fix

- Upgrade GitLab EE to `19.3.6`, `19.4.3`, or `19.5.1` (or later on the same line)
- Until patched, review project and group memberships created or accepted around the time the membership lock was enabled

## Timeline

- 2026-10-23T21:57:30+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-16255
- 2026-10-24T07:15:52+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-16255

## From the sources

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.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_