GitLabApplication
CVE-2026-2973
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 17.7 before 18.8.7, 18.9 before 18.9.3, and 18.10 before 18.10.1 that could have allowed an authenticated user to execute arbitrary JavaScript in a user's browser due to improper sanitization of entity-encoded content in Mermaid diagrams.
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 contains a stored XSS vulnerability where authenticated users can inject arbitrary JavaScript through Mermaid diagrams due to improper sanitization of entity-encoded content. When other users view the affected Mermaid diagram, the malicious payload executes in their browsers.
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
>= 17.7.0, < 18.8.7>= 18.9.0, < 18.9.3= 18.10.0CVSS 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
- 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 checksWork through these to decide whether this CVE applies to you.
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Identify your GitLab versionRun `sudo gitlab-rake gitlab:env:info` or check the GitLab admin panel under Help > Version to find the exact installed version.Affected if The installed version falls within any of these ranges: >= 17.7.0 and < 18.8.7, >= 18.9.0 and < 18.9.3, or equals 18.10.0
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Confirm Mermaid diagram rendering is enabledCheck your GitLab instance settings. Navigate to Settings > Preferences > Markdown or check the markdown_extensions configuration. Alternatively, search for mermaid in the GitLab Rails console with `Gitlab::Markdown::Mermaid.enabled`Affected if Mermaid rendering is enabled and users can create or edit content that supports markdown with Mermaid diagrams
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Verify users have permission to create or edit contentReview user roles and project/group permissions. Check if authenticated users can create issues, merge requests, wikis, or other markdown-rendered content where Mermaid diagrams can be embedded.Affected if Authenticated users have the ability to create or edit markdown content that renders Mermaid diagrams
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Audit existing Mermaid diagram contentSearch your GitLab instance for mermaid diagram usage. Use the API or database to find notes, issues, merge requests, or wikis containing mermaid code blocks. In the Rails console: `Note.with_notes_having_mermaid` or search the database for 'mermaid' in note fields.Affected if Any Mermaid diagram content exists in the system that was created by users who could have injected malicious payloads
Your environment is affected if the installed GitLab version is within the affected ranges AND Mermaid diagram rendering is enabled for users who can create or edit markdown content.
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 · scoped18.8.718.9.3
Upgrade to GitLab versions 18.8.7, 18.9.3, 18.10.1 or later. If immediate patching is not possible, restrict or disable Mermaid diagram rendering until the patch can be applied.
18.8.7, 18.9.3, or 18.10.1 (or later stable release)
- 1. Identify the current GitLab version by navigating to Admin Area > Metrics and Graphs > Version, or running `gitlab-rake gitlab:env:info`
- 2. Determine the appropriate upgrade path based on current version: if on 17.7.x-18.7.x upgrade to 18.8.7; if on 18.9.x upgrade to 18.9.3; if on 18.10.0 upgrade to 18.10.1
- 3. Review GitLab upgrade documentation for your installation method ( Omnibus or source) at https://docs.gitlab.com/ee/update/
- 4. Create a full backup of the GitLab instance before upgrading using `gitlab-backup-create`
- 5. Stop GitLab services with `gitlab-ctl stop`
- 6. Install the target version using your package manager or source installation method
- 7. Reconfigure GitLab with `gitlab-ctl reconfigure`
- 8. Verify the upgrade was successful by checking the version in Admin Area or running `gitlab-rake gitlab:env:info`
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in GitLab
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 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 $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-2973 — 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-2026-2973 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
- No spam, self-promotion, credentials, or personal data