Shibboleth XMLTooling before 3.2.4, as used in OpenSAML and Shibboleth Service Provider, allows SSRF via a crafted KeyInfo element. (This is fixed in, for example, Shibboleth Service Provider 3.4.1.3 on Windows.)
https://www.debian.org/security/2023/dsa-5432
https://shibboleth.net/community/advisories/secadv_20230612.txt