The OpenSAML C++ library before 3.3.1 allows forging of signed SAML messages via parameter manipulation (when using SAML bindings that rely on non-XML signatures).
https://shibboleth.net/community/advisories/secadv_20250313.txt
https://shibboleth.atlassian.net/browse/CPPOST-126
https://lists.debian.org/debian-security-announce/2025/msg00041.html