The (1) BasicParserPool, (2) StaticBasicParserPool, (3) XML Decrypter, and (4) SAML Decrypter in Shibboleth OpenSAML-Java before 2.6.1 set the expandEntityReferences property to true, which allows remote attackers to conduct XML external entity (XXE) attacks via a crafted XML DOCTYPE declaration.

Shibboleth OpenSAML library 2.4.x before 2.4.3 and 2.5.x before 2.5.1, and IdP before 2.3.2, allows remote attackers to forge messages and bypass authentication via an "XML Signature wrapping attack."

OpenSAML 2.x before 2.2.1 and XMLTooling 1.x before 1.2.1, as used by Internet2 Shibboleth Service Provider 2.x before 2.2.1, do not follow the KeyDescriptor element's Use attribute, which allows remote attackers to use a certificate for both signing and encryption when it is designated for just one purpose, potentially weakening the intended security application of the certificate.

Buffer overflow in OpenSAML before 1.1.3 as used in Internet2 Shibboleth Service Provider software 1.3.x before 1.3.4, and XMLTooling before 1.2.2 as used in Internet2 Shibboleth Service Provider software 2.x before 2.2.1, allows remote attackers to cause a denial of service and possibly execute arbitrary code via a malformed encoded URL.