CVE 2011-1411
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."
See the 
CVE page on Mitre.org
for more details.
