CVE-2026-53944Medium· 5.8▾ SunlitGhost: Private IP filtering bypass to make server-side requests to internal services
▾ Sunlit zone — Low / medium · no exploitation signal
impact 31.9 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Aug 4.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via GHSA
0.2%
0.2% → 0.3%
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 present in Ghost from v6.0.9 up to v6.21.0.
v6.21.1 contains a fix for this issue.
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.
Ghost thanks l3tchupkt for disclosing this vulnerability responsibly.
If you have any questions or comments about this advisory, email us at [email protected].
ghost >= 6.0.9, <= 6.21.0Upgrade to a patched release:
ghost 6.21.1Connected by shared product, vendor, weakness, or advisory.
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