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GitLabApplication

CVE-2026-1456

HIGH · 7.5 CVSS v3.1 Published 2026-02-11
Fix available
A fix is available. Upgrade to 18.7.4 / 18.8.4 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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
GitLab has remediated an issue in GitLab CE/EE affecting all versions from 18.7 before 18.7.4, and 18.8 before 18.8.4 that could have allowed an unauthenticated user to cause denial of service through CPU exhaustion by submitting specially crafted markdown files that trigger exponential processing in markdown preview.

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

GitLab CE/EE versions 18.7 before 18.7.4 and 18.8 before 18.8.4 contain a denial-of-service vulnerability in the markdown preview feature. An unauthenticated attacker can submit specially crafted markdown files containing nested or recursive structures that trigger exponential processing time, leading to CPU exhaustion and service unavailability.

MitigationUpgrade GitLab to version 18.7.4, 18.8.4, or later. Until patched, consider disabling or rate-limiting unauthenticated markdown preview functionality at the proxy or application level.

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:>= 18.7.0, < 18.7.4>= 18.8.0, < 18.8.4

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
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 checks

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

  1. Determine your installed GitLab version
    Run 'sudo gitlab-rake gitlab:env:info' or check /opt/gitlab/version to obtain the exact version number
    Affected if The version falls within 18.7.0 to 18.7.3 or 18.8.0 to 18.8.3
  2. Verify if markdown preview is accessible to unauthenticated users
    Attempt to access the markdown preview endpoint without authentication, or review GitLab settings under Settings > General > Visibility and access controls for 'Markdown preview' or 'Project API' settings that allow unauthenticated access
    Affected if Unauthenticated markdown preview functionality is enabled and exposed to the internet
  3. Check for CPU exhaustion or slow markdown processing
    Monitor system CPU usage during markdown rendering, or review GitLab logs (/var/log/gitlab/gitlab-rails/production.log) for markdown-related requests showing excessive processing time
    Affected if Requests to markdown preview endpoints cause disproportionate CPU usage or timeouts

You are affected if your GitLab version is 18.7.0-18.7.3 or 18.8.0-18.8.3 AND unauthenticated markdown preview is accessible to external users.

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 18.7.4 / 18.8.4 or later
Fixed in 18.7.418.8.4
Interim mitigation

Upgrade GitLab to version 18.7.4, 18.8.4, or later. Until patched, consider disabling or rate-limiting unauthenticated markdown preview functionality at the proxy or application level.

Recommended fix High confidence

Upgrade to GitLab 18.7.4 or 18.8.4 (whichever is the latest in your minor branch)

  1. Review the GitLab upgrade documentation for your installation method (omnibus, source, or helm chart)
  2. Ensure you have a complete backup of your GitLab instance before upgrading
  3. Plan for appropriate maintenance window as upgrade may require downtime
  4. Stop GitLab services before upgrade if required by your installation method
  5. For package-based installations (Omnibus), run: sudo apt-get update && sudo apt-get install gitlab-ce (or gitlab-ee) to upgrade to the latest patch version
  6. For source installations, clone the specific tag (e.g., v18.7.4 or v18.8.4) and follow upgrade instructions
  7. Verify the upgrade completed successfully by checking GitLab version in Admin Area > Settings > General
  8. Test markdown rendering functionality to confirm the vulnerability is remediated
Caveat Standard GitLab upgrades may include database migrations; review release notes for any breaking changes between your current version and target 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
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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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-2026-1456 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