dbcve.org
Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 24 Feb 2026.
GitLabApplication

CVE-2021-39935

HIGH · 7.5 CVSS v3.1 Published 2021-12-13
Fix available
A fix is available. Upgrade to 14.3.6 / 14.4.4 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Server-Side Request Forgery (SSRF) vulnerability in GitLab's CI Lint API allows unauthenticated external users to make the GitLab server perform arbitrary HTTP requests to internal or external resources, potentially exposing internal services.

MitigationUpgrade GitLab to version 14.3.6, 14.4.4, 14.5.2 or later. If immediate upgrade is not possible, consider restricting network access to the CI Lint API endpoint or implementing additional authentication controls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
GitLabApplication
Affected:>= 10.5.0, < 14.3.6>= 14.4.0, < 14.4.4>= 14.5.0, < 14.5.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed GitLab version
    Run `sudo gitlab-rake gitlab:env:info` or check the GitLab admin panel under 'Help' > 'Version' to find the exact version number
    Affected if The version falls within >= 10.5.0, < 14.3.6 OR >= 14.4.0, < 14.4.4 OR >= 14.5.0, < 14.5.2
  2. Verify CI Lint API endpoint exposure
    Attempt to access the CI Lint API endpoint (typically /api/v4/ci_lint) without authentication using a curl request: `curl -s -X POST https://your-gitlab-instance/api/v4/ci_lint -H 'Content-Type: application/json' -d '{"content": ".gitlab-ci.yml"}'`
    Affected if The API responds without requiring authentication, indicating the endpoint is accessible to external users
  3. Confirm unauthorized request capability
    Send a test CI lint request to an internal URL (such as http://localhost or an internal service) within the YAML content to observe if the server attempts to fetch it
    Affected if The server successfully makes requests to internal or arbitrary URLs provided in the CI lint content, demonstrating the SSRF vulnerability is exploitable

You are affected if your GitLab version is within the vulnerable ranges AND the CI Lint API is accessible to unauthorized users, allowing them to trigger arbitrary server-side requests.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 14.3.6 / 14.4.4 / 14.5.2 or later
Fixed in 14.3.614.4.414.5.2
Interim mitigation

Upgrade GitLab to version 14.3.6, 14.4.4, 14.5.2 or later. If immediate upgrade is not possible, consider restricting network access to the CI Lint API endpoint or implementing additional authentication controls.

Recommended fix High confidence

Upgrade to GitLab 14.3.6, 14.4.4, or 14.5.2 (or later in the respective release branch)

  1. 1. Back up your GitLab instance database and repository data before starting the upgrade
  2. 2. Ensure your current GitLab version matches one of the affected versions (10.5.0 to 14.3.5, 14.4.0 to 14.4.3, or 14.5.0 to 14.5.1)
  3. 3. For GitLab installations using omnibus packages: run 'sudo gitlab-ctl stop' to stop GitLab services
  4. 4. Update your package repository and install the updated GitLab package
  5. 5. For omnibus installations: run 'sudo gitlab-ctl restart' to apply the upgrade
  6. 6. Verify the upgrade was successful by checking the GitLab version in the Admin Area > Settings > General
  7. 7. Confirm the CI Lint API now properly restricts requests from unauthorized external users
Caveat Review GitLab release notes for your target version for any known breaking changes or required migration steps

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in GitLab Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-39935 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-39935 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data