Ghost: Private IP Filtering Bypass via IPv6 Transition Addresses

### Impact A validation issue allowed some functionality, such as Webmentions, to be abused by an unauthenticated user to make limited HTTP requests to hosts in the Ghost server's internal network on some network configurations. A successful attack would not result in any response data being returned. ### Vulnerable versions This vulnerability is present in Ghost from v6.0.9 up to v6.64.0. ### Patches v6.65.0 contains a fix for this issue. ### How to update For 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). If your Ghost is a Ghost-CLI install see our documentation on [updating it to the latest version here](https://docs.ghost.org/update). ### References Ghost thanks [Nhat Anh Vu](https://github.com/nhattanhh) for disclosing this vulnerability responsibly. ### For more information If you have any questions or comments about this advisory, email us at [[email protected]](mailto:[email protected]).

Source published

7 Oct 2026 20:35:27 UTC

Source modified

13 Oct 2026 08:26:02 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:N/A:N

Publisher rating · MODERATE