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GitLabApplication

CVE-2023-4912

MEDIUM · 6.5 CVSS v3.1 Published 2023-12-01
Fix available
A fix is available. Upgrade to 16.4.3 / 16.5.3 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable Zero-click

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 EE affecting all versions starting from 10.5 before 16.4.3, all versions starting from 16.5 before 16.5.3, all versions starting from 16.6 before 16.6.1. It was possible for an attacker to cause a client-side denial of service using malicious crafted mermaid diagram input.

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 client-side denial of service vulnerability exists in GitLab EE where maliciously crafted mermaid diagram input can cause the victim's browser to become unresponsive or crash. This affects all versions from 10.5 through the unpatched versions of 16.4.x, 16.5.x, and 16.6.x.

MitigationUpgrade GitLab EE to version 16.4.3, 16.5.3, or 16.6.1 (or later) to patch the vulnerability. Alternatively, restrict or sanitize mermaid diagram input from untrusted sources until upgrade is possible.

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:>= 10.5.0, < 16.4.3>= 16.5.0, < 16.5.3= 16.6.0

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
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Determine installed GitLab version
    Run `sudo gitlab-rake gitlab:env:info` or check the GitLab admin panel under Help > Version. Alternatively, check the /opt/gitlab/version file or run `gitlab --version`.
    Affected if The version is 10.5.0 or higher but below 16.4.3, OR 16.5.0 to below 16.5.3, OR exactly 16.6.0.
  2. Confirm GitLab edition is EE
    The vulnerability affects GitLab Enterprise Edition (EE). Check the version output or admin panel - it will show 'GitLab Enterprise Edition' if affected edition.
    Affected if The installation is GitLab EE (not CE).
  3. Identify mermaid diagram usage
    Search repositories or wikis for `.mmd` files or mermaid code blocks (```mermaid blocks) in projects. In admin area, review projects or files that may contain mermaid diagram markup.
    Affected if Mermaid diagrams exist in any accessible project, wiki, or markdown content in the GitLab instance.

A GitLab EE installation is affected if its version falls within 10.5.0 to 16.4.2, 16.5.0 to 16.5.2, or exactly 16.6.0, and mermaid diagram rendering is enabled (the default behavior).

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 16.4.3 / 16.5.3 or later
Fixed in 16.4.316.5.3
Interim mitigation

Upgrade GitLab EE to version 16.4.3, 16.5.3, or 16.6.1 (or later) to patch the vulnerability. Alternatively, restrict or sanitize mermaid diagram input from untrusted sources until upgrade is possible.

Recommended fix High confidence

Upgrade to 16.4.3 (if on 16.4.x), 16.5.3 (if on 16.5.x), or 16.6.1 (if on 16.6.x)

  1. 1. Backup your GitLab instance data before upgrading
  2. 2. Identify your current GitLab version using `gitlab-rake gitlab:env:info`
  3. 3. For GitLab 16.4.x: Upgrade to version 16.4.3 or later
  4. 4. For GitLab 16.5.x: Upgrade to version 16.5.3 or later
  5. 5. For GitLab 16.6.0: Upgrade to version 16.6.1 or later
  6. 6. Verify the upgrade was successful by checking the GitLab version after restart
  7. 7. Test that Mermaid diagram rendering works correctly in issues, merge requests, and wikis
Caveat Standard GitLab upgrade considerations apply - review release notes for any breaking changes between your current and target version

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

Fix this in GitLab Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,544.

Scan for this in your stack

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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-2023-4912 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