The (1) HttpResource and (2) FileBackedHttpResource implementations in Shibboleth Identity Provider (IdP) before 2.4.1 and OpenSAML Java 2.6.2 do not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.

The DynamicMetadataProvider class in saml/saml2/metadata/impl/DynamicMetadataProvider.cpp in OpenSAML-C in OpenSAML before 2.6.1 fails to properly configure itself with the MetadataFilter plugins and does not perform critical security checks such as signature verification, enforcement of validity periods, and other checks specific to deployments, aka CPPOST-105.

The PKIX trust engines in Shibboleth Identity Provider before 2.4.4 and OpenSAML Java (OpenSAML-J) before 2.6.5 trust candidate X.509 credentials when no trusted names are available for the entityID, which allows remote attackers to impersonate an entity via a certificate issued by a shibmd:KeyAuthority trust anchor.

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.