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GitLabApplication

CVE-2021-39877

MEDIUM · 5.5 CVSS v3.1 Published 2021-10-04
Fix available
A fix is available. Upgrade to 14.1.7 / 14.2.5 or later.
See remediation →
58/100
Remediation priority · Elevated
No privileges

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
A vulnerability was discovered in GitLab starting with version 12.2 that allows an attacker to cause uncontrolled resource consumption with a specially crafted file.

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

A vulnerability in GitLab versions 12.2 and later allows attackers to cause uncontrolled resource consumption by uploading a specially crafted file. This is a denial-of-service vulnerability that exploits insufficient handling of certain file types during processing.

MitigationUpgrade to the patched version of GitLab as specified in the official GitLab security release. Implement rate limiting and file size restrictions on file uploads as a defense-in-depth measure.

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:>= 12.2.0, < 14.1.7>= 14.2, < 14.2.5>= 14.3, < 14.3.1

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
Local
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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. Identify the installed GitLab version
    Run `cat /opt/gitlab/version` or check the GitLab admin dashboard under Help > Version. Alternatively, use the command `gitlab-rake gitlab:env:info` to retrieve version details.
    Affected if The installed version falls within the affected ranges: 12.2.0 to 14.1.6, 14.2.0 to 14.2.4, or 14.3.0.
  2. Confirm file upload functionality is enabled
    Check if the file upload feature is accessible. In GitLab, this typically applies to project uploads, issue attachments, or merge request diffs. Verify via admin settings under Settings > General > Visibility and access controls, or inspect whether users with reporter or guest roles can upload files.
    Affected if File uploads are enabled and accessible to users who can create issues, merge requests, or upload attachments.
  3. Verify external user access is permitted
    Review GitLab authentication settings. Check if anonymous or external users have access to repositories and can interact with file upload features. Inspect admin area under Settings > General > Visibility and access controls, and review which projects allow external contributor access.
    Affected if Anonymous users or external users without full authentication can upload files to projects.
  4. Assess rate limiting and file upload limits
    Inspect the GitLab configuration file at `/etc/gitlab/gitlab.rb` for `nginx['client_max_body_size']` and rate limiting settings. Also check in the Rails application under Admin Area > Settings > Network > Output rate limits and related upload restrictions.
    Affected if No rate limiting is configured on file uploads or the limits are set excessively high, allowing rapid repeated uploads.

You are affected if your GitLab version is 12.2.0-14.1.6, 14.2.0-14.2.4, or 14.3.0 AND file uploads are accessible to users who could exploit the resource consumption issue.

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 14.1.7 / 14.2.5 / 14.3.1 or later
Fixed in 14.1.714.2.514.3.1
Interim mitigation

Upgrade to the patched version of GitLab as specified in the official GitLab security release. Implement rate limiting and file size restrictions on file uploads as a defense-in-depth measure.

Recommended fix High confidence

Upgrade to GitLab 14.1.7, 14.2.5, 14.3.1 or later stable release

  1. 1. Backup your GitLab instance database and repository data before proceeding with the upgrade
  2. 2. Ensure your current GitLab version falls within one of the affected ranges: 12.2.0-14.1.6, 14.2.0-14.2.4, or 14.3.0
  3. 3. For GitLab installations using the official omnibus package, run: sudo gitlab-ctl stop
  4. 4. Update your GitLab package using your distribution's package manager (e.g., apt-get update && apt-get install gitlab-ce for Debian/Ubuntu, or yum install for RHEL/CentOS)
  5. 5. Alternatively, for Docker installations, pull the fixed version: docker pull gitlab/gitlab-ee:14.3.1 (or latest 14.3.x stable)
  6. 6. Run sudo gitlab-ctl reconfigure after package installation
  7. 7. Verify the upgrade completed successfully with sudo gitlab-rake gitlab:env:info
  8. 8. Confirm the vulnerability is resolved by checking the GitLab version shows 14.1.7, 14.2.5, 14.3.1 or later
Caveat This is a patch release; minimal breaking changes expected. Always review GitLab release notes before upgrading in production environments.

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

Fix this in GitLab Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
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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-2021-39877 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