What is CVE-2021-39947?

CVE-2021-39947 is a medium-severity vulnerability in GitLab Runner. CVSS score: 5.3/10. Published 2022-06-06.

How severe is CVE-2021-39947?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in GitLab Runner

CVE-2021-39947

In specific circumstances, trace file buffers in GitLab Runner versions up to 14.3.4, 14.4 to 14.4.2, and 14.5 to 14.5.2 would re-use the file descriptor 0 for multiple traces and mix the output of several jobs

Published 2022-06-06 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.008 (56.0th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 56th percentile — 56.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

GitLab Runner — versions <14.3.4, >=14.4, <14.4.2, >=14.5, <14.5.2
GitLab Runner

References

gitlab.com/gitlab-org/gitlab-runner/-/issues/28732 (Broken Link)
gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39947.json (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-39947?: CVE-2021-39947 is a medium-severity vulnerability in GitLab Runner. CVSS score: 5.3/10. Published 2022-06-06.
How severe is CVE-2021-39947?: Medium severity. CVSS v3 base score is 5.3 out of 10.