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CWE-184Weakness · CWE-184

CVE-2026-53944

MEDIUM · 5.8 CVSS v3.1 Published 2026-06-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
67/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 8 weeks old

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
Ghost is a Node.js content management system. From 6.0.9 until 6.21.1, when making an external request, it is possible to bypass the IP filter that ensures the request isn't going to an internal service using an IPv6 literal which maps to a private IPv4 address. This vulnerability is fixed in 6.21.1.

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

Ghost CMS contains an SSRF vulnerability where the IP filter designed to block requests to internal/private networks can be bypassed using IPv6 literal representations that map to private IPv4 addresses (e.g., IPv6-mapped IPv4 addresses). An attacker can use addresses like ::ffff:192.168.x.x to access internal services that should be protected.

MitigationUpgrade Ghost to version 6.21.1 or later, which includes proper IPv6 handling in the IP filter validation logic.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/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 checks

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

  1. Check Ghost CMS version
    Run 'ghost version' in the CLI or check the package.json file in the Ghost installation directory. Alternatively, access /ghost/api/admin/site/ via the admin API and look at the response for the version field.
    Affected if The installed version is earlier than 6.21.1 (e.g., 6.20.0, 6.0.0, 5.x.x)
  2. Verify internal network filtering is in use
    Check if Ghost is configured to fetch external resources or if webhooks/API integrations that could make outbound requests are enabled. Look for configuration in config.development.json or config.production.json files under the 'url' or 'adapter' settings.
    Affected if The system makes outbound HTTP requests to user-controlled URLs or has features like custom integrations, webhooks, or sitemap fetching enabled
  3. Inspect IP filtering implementation
    Examine the Ghost source code in the /core/server/lib/ directory for files related to IP validation, such as any file containing 'ip', 'filter', 'private', or 'internal' in the filename. Look for the IP blocking logic.
    Affected if The IP validation code does not explicitly handle IPv6-mapped IPv4 addresses (::ffff: prefix) or lacks specific checks for these addresses
  4. Test for IPv6 bypass manually
    If you have access to a feature that accepts URLs (e.g., custom integration endpoint, webhook URL field), attempt to input a URL with an IPv6-mapped private address such as http://[::ffff:192.168.1.1]:8080/ or http://[::ffff:10.0.0.1]/internal and observe if the request is allowed or blocked.
    Affected if Requests to internal IPv4 addresses via IPv6-mapped notation (::ffff:x.x.x.x) are permitted when they should be denied

A system is affected if it runs Ghost CMS version earlier than 6.21.1 and has features that allow external URLs to be specified, as the IP filter can be bypassed via IPv6-mapped IPv4 addresses.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade Ghost to version 6.21.1 or later, which includes proper IPv6 handling in the IP filter validation logic.

Recommended fix High confidence

Ghost 6.21.1 or later

  1. Backup your Ghost installation and database before upgrading
  2. Upgrade Ghost to version 6.21.1 or later by running the appropriate upgrade command for your installation method (e.g., `ghost update` or via your package manager)
  3. Verify the upgrade was successful and test that external requests function correctly
Caveat Review Ghost's release notes for any breaking changes between your current version and 6.21.1

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,780
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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-2026-53944 in production — separate from our analysis above.

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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
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  • Version or environment caveats, and links to real fixes
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