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GitLabApplication

CVE-2021-39940

MEDIUM · 6.5 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 →
71/100
Remediation priority · Elevated
Remotely reachable 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 13.2 before 14.3.6, all versions starting from 14.4 before 14.4.4, all versions starting from 14.5 before 14.5.2. GitLab Maven Package registry is vulnerable to a regular expression denial of service when a specifically crafted string is sent.

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

GitLab's Maven Package Registry contains a regular expression denial of service (ReDoS) vulnerability. An attacker can send a specifically crafted string to the Maven registry endpoint that causes the regex engine to take an extremely long time to process, leading to service degradation or unavailability.

MitigationUpgrade GitLab to version 14.3.7, 14.4.5, 14.5.3, or later. Alternatively, if immediate patching is not feasible, consider restricting access to the Maven Package Registry or implementing rate limiting on the affected endpoint.

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:>= 13.2.0, < 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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

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. Check your GitLab version
    Retrieve the installed GitLab version from your instance admin area or by running `gitlab-rake gitlab:env:info` on the server. Compare the version number against the affected ranges: 13.2.0 through 14.3.5, 14.4.0 through 14.4.3, or 14.5.0 through 14.5.1.
    Affected if The installed version falls within any of the affected ranges listed above.
  2. Verify Maven Package Registry is enabled
    Navigate to the GitLab admin area under Packages and Registries settings, or check the GitLab configuration file for Maven Registry settings. Confirm whether the Maven Package Registry feature is turned on.
    Affected if The Maven Package Registry is enabled in the GitLab instance.
  3. Confirm Maven registry endpoint is accessible
    Attempt to access the Maven Package Registry endpoint on your GitLab instance (typically at /api/v4/projects/<project_id>/packages/maven). Determine if the endpoint responds to requests.
    Affected if The Maven registry endpoint is reachable from the network where an attacker could send requests.

Your environment is affected if your GitLab version is between 13.2.0 and 14.3.5, 14.4.0 and 14.4.3, or 14.5.0 and 14.5.1 AND the Maven Package Registry is enabled and accessible to potential attackers.

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 14.3.7, 14.4.5, 14.5.3, or later. Alternatively, if immediate patching is not feasible, consider restricting access to the Maven Package Registry or implementing rate limiting on the affected endpoint.

Recommended fix Moderate confidence

GitLab 14.5.2 or later (or latest stable 14.10.x/15.x)

  1. Back up your GitLab instance data and configuration before upgrading
  2. Check your current GitLab version in the Admin Area > Monitoring > Version check
  3. Follow the official GitLab upgrade documentation for your current version to reach the target version
  4. For versions 13.2.0 to 14.3.x: upgrade to GitLab 14.3.6 or later
  5. For versions 14.4.0 to 14.4.x: upgrade to GitLab 14.4.4 or later
  6. For versions 14.5.0 to 14.5.x: upgrade to GitLab 14.5.2 or later
  7. Alternatively, upgrade directly to the latest stable GitLab release (14.10.x or later) which contains the fix
  8. After upgrade, verify the Maven Package registry functionality works correctly
Caveat GitLab upgrades between major versions may include breaking changes; review release notes for deprecations and migration requirements before upgrading

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

Fix this in GitLab Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2021-39940 in production — separate from our analysis above.

No notes yet

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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