SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. When loading an (untrusted) XML document, for example the SAMLResponse, it's possible to induce an XXE. This vulnerability is fixed in 4.6.14 and 5.0.0-alpha.18.
https://github.com/simplesamlphp/saml2/security/advisories/GHSA-pxm4-r5ph-q2m2
https://github.com/simplesamlphp/saml2/commit/5fd4ce4596656fb0c1278f15b8305825412e89f7