GitLabApplication
CVE-2026-5816
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 · uneditedGitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.10 before 18.10.4 and 18.11 before 18.11.1 that could have allowed an unauthenticated user to execute arbitrary JavaScript in a user's browser session due to improper path validation under certain conditions.
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 confidenceGitLab CE/EE contains a cross-site scripting (XSS) vulnerability caused by improper path validation. An unauthenticated attacker can inject arbitrary JavaScript that executes in the browser session of authenticated users, potentially leading to session hijacking or credential theft.
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
>= 18.10.0, < 18.10.4= 18.11.0CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 checksWork through these to decide whether this CVE applies to you.
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Check installed GitLab versionRun `sudo gitlab-rake gitlab:version` or check the GitLab admin panel under Help > Version. Alternatively, check the package version with `dpkg -l | grep gitlab` or `rpm -q gitlab-ce` depending on your package manager.Affected if The version is 18.10.0 through 18.10.3, or exactly 18.11.0
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Confirm GitLab is exposed to unauthenticated usersVerify whether the GitLab instance allows anonymous or unauthenticated access to web interfaces, projects, or APIs. Check the 'Application Settings' in the Admin area under 'Visibility and access controls'.Affected if Anonymous or unauthenticated users have access to any GitLab web path or API endpoint, as the flaw allows unauthenticated attackers to inject XSS
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Review web server access logs for anomalous path requestsExamine GitLab web logs (typically in /var/log/gitlab/nginx/gitlab_access.log) for unusual URL patterns with JavaScript payloads or path traversal sequences that may indicate exploitation attempts.Affected if Suspicious patterns containing `<script>` tags, `javascript:`, or encoded XSS vectors appear in access logs targeting path-related endpoints
You are affected if your GitLab version falls within 18.10.0-18.10.3 or 18.11.0 and the instance is accessible to unauthenticated users, enabling the path validation flaw to be exploited for stored XSS.
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 · scoped18.10.4
Upgrade GitLab to version 18.10.4 or 18.11.1 or later to remediate this vulnerability.
18.10.4 (for 18.10.x) or 18.11.1 (for 18.11.x)
- Identify currently installed GitLab version using 'gitlab-rake gitlab:env:info' or the GitLab admin dashboard
- For GitLab 18.10.x (versions 18.10.0-18.10.3): Plan upgrade to version 18.10.4 or later
- For GitLab 18.11.0: Plan upgrade to version 18.11.1 or later
- Review GitLab upgrade documentation for your deployment method (omnibus, source, etc.)
- Create a full backup of your GitLab instance before proceeding with the upgrade
- Execute the upgrade following GitLab's standard upgrade path documentation
- Verify the upgrade was successful and GitLab services are running
- Confirm the version after upgrade matches the expected fixed version
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
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-5816 — 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-2026-5816 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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- 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