An XXE issue was discovered in Morpheus through 5.2.16 and 5.4.x through 5.4.4. A successful attack requires a SAML identity provider to be configured. In order to exploit the vulnerability, the attacker must know the unique SAML callback ID of the configured identity source. A remote attacker can send a request crafted with an XXE payload to invoke a malicious DTD hosted on a system that they control. This results in reading local files that the application has access to.