GitLabApplication
CVE-2025-2256
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 · uneditedAn issue has been discovered in GitLab CE/EE affecting all versions from 7.12 before 18.1.6, 18.2 before 18.2.6, and 18.3 before 18.3.2 that could have allowed unauthorized users to render the GitLab instance unresponsive to legitimate users by sending multiple concurrent large SAML responses.
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 confidenceA denial of service vulnerability in GitLab CE/EE allows unauthenticated attackers to send multiple concurrent large SAML authentication responses that consume excessive server resources, rendering the instance unresponsive to legitimate users.
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
>= 7.12.0, < 18.1.6>= 18.2.0, < 18.2.6>= 18.3.0, < 18.3.2CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Verify GitLab SAML authentication is enabledNavigate to Admin Area > Settings > Authentication and Authorization > SAML Single Sign-On, or check /etc/gitlab/gitlab.rb for 'gitlab_rails["omniauth_providers"]' containing 'saml' configurationAffected if SAML authentication is configured and enabled on the GitLab instance
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Check the installed GitLab versionRun 'gitlab-rake gitlab:env:info' or check /opt/gitlab/version, or use the GitLab admin dashboard under Help > VersionAffected if The installed version falls within: 7.12.0 to 18.1.5, 18.2.0 to 18.2.5, or 18.3.0 to 18.3.1
The instance is affected if SAML authentication is enabled AND the installed GitLab version is within the vulnerable ranges listed.
Generated from the published advisory. Verify against your own configuration.
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 · scoped18.1.618.2.618.3.2
Upgrade GitLab to version 18.1.6, 18.2.6, or 18.3.2 or later. Consider implementing rate limiting on SAML endpoints as a temporary mitigation while planning the upgrade.
18.3.2 or later (or 18.2.6+, or 18.1.6+)
- Schedule a maintenance window for the GitLab upgrade
- Back up the GitLab database and repositories
- Upgrade GitLab to version 18.1.6, 18.2.6, or 18.3.2 (or later in any of these minor release lines)
- After upgrade, verify SAML authentication is functioning correctly
- Monitor GitLab instance performance to confirm the DoS vulnerability is mitigated
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in GitLab
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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 locallyCheck whether your project pulls in CVE-2025-2256 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-2256 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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
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