CVE-2026-1388 Inefficient Regular Expression Complexity in GitLab

What is CVE-2026-1388?

CVE-2026-1388 is a high-severity denial of service vulnerability in Gitlab Gitlab, published on 25 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

GitLab has remediated an issue in GitLab CE/EE affecting all versions from 9.2 before 18.7.5, 18.8 before 18.8.5, and 18.9 before 18.9.1 that could have allowed an unauthenticated user to cause regular expression denial of service by sending specially crafted input to a merge request endpoint under certain conditions.

Weakness: CWE-1333

Which versions are affected by CVE-2026-1388?

1 open source package ship an affected version, including gitlab. It affects 1 product.

Products include Gitlab Gitlab.

How do I fix CVE-2026-1388?

Upgrade gitlab to a fixed version for your release line: 18.7.5, 18.8.5 or 18.9.1.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-1388 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-1388 exists.

Other vulnerabilities in Gitlab Gitlab

• CVE-2026-97229 GitLab Community Edition and Enterprise Edition Integer Overflow or Wraparound Exploited Critical 10.0
• CVE-2026-85706 GitLab Community Edition and Enterprise Edition Path Traversal Exploited Critical 10.0
• CVE-2023-7028 GitLab Community and Enterprise Editions Improper Access Control Exploited Critical 10.0
• CVE-2021-22205 GitLab Community and Enterprise Editions Remote Code Execution Exploited Critical 10.0
• CVE-2021-39935 GitLab Community and Enterprise Editions Server-Side Request Forgery (SSRF) Exploited Medium 6.8

All Gitlab Gitlab vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BIT-gitlab-2026-1388, GHSA-35pf-5r93-c5jc, UBUNTU-CVE-2026-1388.