CVE-2021-39939 Denial of service in GitLab Runner

What is CVE-2021-39939?

CVE-2021-39939 is a medium-severity denial of service vulnerability in Gitlab Gitlab, published on 13 Dec 2021. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

An uncontrolled resource consumption vulnerability in GitLab Runner affecting all versions starting from 13.7 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2, allows an attacker triggering a job with a specially crafted docker image to exhaust resources on runner manager

Weakness: CWE-400

Which versions are affected by CVE-2021-39939?

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

Products include Gitlab Gitlab.

How do I fix CVE-2021-39939?

Upgrade gitlab to a fixed version for your release line: 14.3.6, 14.4.4 or 14.5.2.

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-2021-39939 being exploited?

There is no known exploitation of CVE-2021-39939 in the wild and no public exploit code.

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-2021-39939, GHSA-9jvc-93xj-9mfg, UBUNTU-CVE-2021-39939.