{"id":"CVE-2026-53944","aliases":["GHSA-wvp2-4qqp-4h3r"],"title":"Ghost: Private IP filtering bypass to make server-side requests to internal services","summary":"Ghost: Private IP filtering bypass to make server-side requests to internal services","severity":"medium","cvss":5.8,"cwe":["CWE-184","CWE-918"],"vendor":"ghost","product":"ghost","ecosystem":"npm","affected":["ghost >= 6.0.9, <= 6.21.0"],"patched":["ghost 6.21.1"],"published":"2026-08-04","updated":"2026-08-04","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-wvp2-4qqp-4h3r","references":[{"url":"https://github.com/TryGhost/Ghost/security/advisories/GHSA-wvp2-4qqp-4h3r"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53944"},{"url":"https://github.com/TryGhost/Ghost/pull/26749"},{"url":"https://github.com/TryGhost/Ghost/commit/9b7f2212970fade08ecbec543b405190471e38d4"},{"url":"https://github.com/TryGhost/Ghost/releases/tag/v6.21.1"},{"url":"https://github.com/advisories/GHSA-wvp2-4qqp-4h3r"}],"tags":["ghsa","npm"],"epss":0.00329,"epssPercentile":0.23212,"ingestedAt":"2026-08-04T21:42:19.458Z","slug":"CVE-2026-53944","body":"## Overview\n\n### Impact\n\nWhen 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.\n\n### Vulnerable versions\n\nThis vulnerability is present in Ghost from v6.0.9 up to v6.21.0.\n\n### Patches\n\nv6.21.1 contains a fix for this issue.\n\n### How to update\n\nFor self-hosters using Docker, find [Docker's official Ghost image here](https://hub.docker.com/_/ghost). Updating a Docker-based Ghost instance [is documented here](https://docs.ghost.org/install/docker#updating-ghost). \n\nIf your Ghost is a Ghost-CLI install see our documentation on [updating it to the latest version here](https://docs.ghost.org/update). \n\n### References\n\nGhost thanks [l3tchupkt](http://github.com/l3tchupkt) for disclosing this vulnerability responsibly.\n\n### For more information\n\nIf you have any questions or comments about this advisory, email us at [security@ghost.org](mailto:security@ghost.org).\n\n## Affected packages\n\n- `ghost >= 6.0.9, <= 6.21.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `ghost 6.21.1`","depth":"sunlit","depthScore":32,"depthScoreParts":{"impact":31.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}