SAML authentication bypass via Incorrect XPath selector

Ruby-SAML in <= 12.2 and 1.13.0 <= 1.16.0 does not properly verify the signature of the SAML Response. An unauthenticated attacker with access to any signed saml document (by the IdP) can thus forge a SAML Response/Assertion with arbitrary contents. This would allow the attacker to log in as arbitrary user within the vulnerable system.

This vulnerability was reported by ahacker1 of SecureSAML (ahacker1@securesaml.com)