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GitLabApplication

CVE-2025-4439

MEDIUM · 5.4 CVSS v3.1 Published 2025-07-23
Fix available
A fix is available. Upgrade to 18.0.5 / 18.1.3 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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 from 15.10 before 18.0.5, 18.1 before 18.1.3, and 18.2 before 18.2.1 that could have allowed an authenticated user to perform cross-site scripting attacks when the instance is served through certain content delivery networks.

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 · moderate confidence

An authenticated user can perform cross-site scripting (XSS) attacks on GitLab CE/EE instances when served through certain content delivery networks. The vulnerability affects versions 15.10 through 18.2.0, specifically before patched releases 18.0.5, 18.1.3, and 18.2.1.

MitigationUpgrade GitLab to version 18.0.5, 18.1.3, 18.2.1 or later. Additionally, review and secure the CDN-to-GitLab header handling to prevent XSS vectors.

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:>= 15.10.0, < 18.0.5>= 18.1.0, < 18.1.3= 18.2

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
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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. Check installed GitLab version via API
    Run `curl -s https://your-gitlab-instance/api/v4/version` or access the version endpoint in your browser. The response will show version numbers in JSON format.
    Affected if The version shown is >= 15.10.0 and < 18.0.5, OR >= 18.1.0 and < 18.1.3, OR = 18.2.0 (any version in the affected ranges).
  2. Check GitLab version via command line
    Run `sudo gitlab-rake gitlab:env:info` on the GitLab server, or check `/opt/gitlab/version` if that path exists on your installation.
    Affected if The reported version falls within the affected ranges listed above.
  3. Determine if GitLab is served through a CDN
    Inspect your web server configuration (nginx/apache) or load balancer settings. Look for upstream CDN configurations, CDN-related headers being passed (such as X-Forwarded-* headers), or CDN-specific proxy settings in front of GitLab.
    Affected if A CDN is configured to proxy traffic to this GitLab instance (the vulnerability only applies in this configuration).
  4. Review CDN header handling configuration
    Examine your web server or load balancer configuration files for how HTTP headers from the CDN are forwarded to GitLab. Check for any configuration that passes raw or unvalidated headers from the CDN directly to the application.
    Affected if The configuration passes headers from the CDN to GitLab without sanitization, creating the XSS vector.

You are affected if your GitLab version is within 15.10.0 to 18.2.0 and your instance is accessed through a CDN that forwards headers to GitLab without sanitization.

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 18.0.5 / 18.1.3 or later
Fixed in 18.0.518.1.3
Interim mitigation

Upgrade GitLab to version 18.0.5, 18.1.3, 18.2.1 or later. Additionally, review and secure the CDN-to-GitLab header handling to prevent XSS vectors.

Recommended fix High confidence

Upgrade to GitLab 18.2.1 or later (18.0.5+ for 18.0.x branch, 18.1.3+ for 18.1.x branch)

  1. 1. Back up your GitLab instance database and configuration files
  2. 2. Plan maintenance window as upgrade may require downtime
  3. 3. For Omnibus installations: Run 'sudo gitlab-ctl stop' to stop services
  4. 4. For source installations: Stop the GitLab service
  5. 5. Update GitLab to version 18.2.1 or later using your installation method (Omnibus: 'sudo apt-get update && sudo apt-get install gitlab-ce' or 'sudo apt-get install gitlab-ee'; Source: pull latest 18.2.x or later tag and rebuild)
  6. 6. After upgrade, run 'sudo gitlab-ctl reconfigure' for Omnibus installations
  7. 7. Verify GitLab is running: 'sudo gitlab-ctl status'
  8. 8. Test that the instance loads properly and check /var/log/gitlab/gitlab-rails/production.log for any errors
Caveat Review GitLab upgrade notes for breaking changes between your current version and 18.2.x; major version upgrades may require additional migration steps

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

Fix this in GitLab Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,800
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.

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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-2025-4439 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