What is CVE-2021-39935?

CVE-2021-39935 is a medium-severity vulnerability in GitLab, classified under Server-Side Request Forgery (SSRF). CVSS score: 6.8/10. Published 2021-12-13.

How severe is CVE-2021-39935?

Medium severity. CVSS v3 base score is 6.8 out of 10.

Is CVE-2021-39935 known to be exploited?

Yes. CVE-2021-39935 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-03), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.

SSRF in GitLab

CVE-2021-39935

An issue has been discovered in GitLab CE/EE affecting all versions starting from 10.5 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. Unauthorized external users could perform Server Side Requests via the CI Lint API

Vulnerability class: SSRF (Server-Side Request Forgery)

Published 2021-12-13 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.361 (98.5th percentile), scored 2026-10-19.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 98.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.356 · newest: 0.361 · change: +0.005

Affected products

GitLab — versions >=10.5, <14.3.6, >=14.4, <14.4.4, >=14.5, <14.5.2

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2026-02-03. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2026-02-24.

Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Public proof-of-concept exploits

References

gitlab.com/gitlab-org/gitlab/-/issues/346187 (Issue Tracking, Vendor Advisory)
hackerone.com/reports/1236965 (Permissions Required, Third Party Advisory)
gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39935.json (Third Party Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2021-39935?: CVE-2021-39935 is a medium-severity vulnerability in GitLab, classified under Server-Side Request Forgery (SSRF). CVSS score: 6.8/10. Published 2021-12-13.
How severe is CVE-2021-39935?: Medium severity. CVSS v3 base score is 6.8 out of 10.
Is CVE-2021-39935 known to be exploited?: Yes. CVE-2021-39935 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-02-03), indicating it is being actively exploited. 2 public proof-of-concept repositories are indexed.