CVE-2026-53944

mediumCVSS 5.8covered by 1 sourcefirst seen 2026-08-04

Impact 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. Vulnerable versions This vulnerability is present in Ghost from v6.0.9 up to v6.21.0. Patches v6.21.1 contains a fix for this issue. How to update For self-hosters using Docker, find Docker's official Ghost image here. Updating a Docker-based Ghost instance is documented here. If your Ghost is a Ghost-CLI install see our documentation on updating it to the latest version here. References Ghost thanks l3tchupkt for disclosing this vulnerability responsibly. For more information If you have any questions or comments about this advisory, email us at security@ghost.org.

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Exploitation outlook

Low exploitation risk0.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 10% of all EPSS-scored CVEs.

Advisory coverage (1)

mediumGHSA-wvp2-4qqp-4h3r: Ghost: Private IP filtering bypass to make server-side requests to internal servicesghsa · 2026-08-04

External references

NVD record for CVE-2026-53944

CVE.org record

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