CVE-2021-39935 on CISA KEV

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

01What CISA says about this vulnerability

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

02Required action — verbatim from CISA

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

03Notes & references

• gitlab.com — https://gitlab.com/gitlab-org/gitlab/-/issues/346187
• hackerone.com — https://hackerone.com/reports/1236965
• gitlab.com — https://gitlab.com/gitlab-org/cves/-/blob/master/2021/CVE-2021-39935.json

04SARA's analyst layer — why this matters

This vulnerability is currently on the CISA KEV list, which CISA only adds CVEs to when there is reliable evidence of active exploitation in the wild. For federal civilian agencies, BOD 22-01 requires remediation by the due date above. For everyone else, KEV is the strongest "patch immediately" signal you can get from public threat intel.

05Affected products (summary)

Vendor	Product	Versions
GitLab	GitLab	>=10.5, <14.3.6, >=14.4, <14.4.4, >=14.5, <14.5.2

06Detection

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection:

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