Description
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 16.11 before 18.7.6, 18.8 before 18.8.6, and 18.9 before 18.9.2 that could have allowed an authenticated user to cause a denial of service condition due to improper input validation on webhook custom header names under certain conditions.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| GitLab | GitLab | 16.11 – < 18.7.6, 18.8 – < 18.8.6, 18.9 – < 18.9.2 | 18.7.6 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | gitlab | No fix yet | — |
Advisories 2
- NCSC-2026-0093 Kwetsbaarheden verholpen in GitLab NCSC-NL (Netherlands) · Mar 12, 2026
- WID-SEC-2026-0697 GitLab: Mehrere Schwachstellen BSI CERT-Bund (WID) · Mar 11, 2026
References
- HackerOne Bug Bounty Report #3415683 technical-description exploit permissions-required
- https://gitlab.com/gitlab-org/gitlab/-/work_items/582096
- https://about.gitlab.com/releases/2026/03/11/patch-release-gitlab-18-9-2-released/