CVE-2021-39935: GitLab Community and Enterprise Editions Server-Side Request Forgery (SSRF) Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 3 Feb 2026, 1,513 days after the CVE record was published.

How likely is exploitation in the next 30 days?

36.1%

EPSS score, percentile 98.5 of all scored records

How severe?

6.8 Medium

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline 24 Feb 2026. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Affected

• >=10.5, <14.3.6
• >=14.4, <14.4.4
• >=14.5, <14.5.2

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 24 February 2026.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://about.gitlab.com/releases/2021/12/06/security-release-gitlab-14-5-2-released/
• https://nvd.nist.gov/vuln/detail/CVE-2021-39935

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

GitLab Community and Enterprise Editions contain a server-side request forgery vulnerability which could allow unauthorized external users to perform Server Side Requests via the CI Lint API.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2021-39935 to its Known Exploited Vulnerabilities (KEV) catalog on 3 Feb 2026.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 24 Feb 2026.
• The CVE record was published on 13 Dec 2021, 1,513 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 6.8 (Medium), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 36.1% (percentile 98.5), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

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

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-918: Server-Side Request Forgery (SSRF)

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• gitlab.com
• hackerone.com
• gitlab.com

More exploited GitLab vulnerabilities

• CVE-2026-85706: GitLab Community Edition and Enterprise Edition Path Traversal Vulnerability (added 11 Sep 2026)
• CVE-2021-22175: GitLab Server-Side Request Forgery (SSRF) Vulnerability (added 18 Feb 2026)
• CVE-2023-7028: GitLab Community and Enterprise Editions Improper Access Control Vulnerability (added 1 May 2024)
• CVE-2021-22205: GitLab Community and Enterprise Editions Remote Code Execution Vulnerability (added 3 Nov 2021)