Gomatrixserverlib is a Go library for matrix federation. Gomatrixserverlib is vulnerable to server-side request forgery, serving content from a private network it can access, under certain conditions. The commit `c4f1e01` fixes this issue. Users are advised to upgrade. Users unable to upgrade should use a local firewall to limit the network segments and hosts the service using gomatrixserverlib can access.
https://github.com/matrix-org/gomatrixserverlib/security/advisories/GHSA-4ff6-858j-r822
https://github.com/matrix-org/gomatrixserverlib/commit/c4f1e01eab0dd435709ad15463ed38a079ad6128