The remote host is missing an update to shibboleth-sp, shibboleth-sp2, opensaml2 announced via advisory DSA 1947-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201947-1

Matt Elder discovered that Shibboleth, a federated web single sign-on system is vulnerable to script injection through redirection URLs. More details can be found in the Shibboleth advisory at http://shibboleth.internet2.edu/secadv/secadv_20091104.txt For the old stable distribution (etch), this problem has been fixed in version 1.3f.dfsg1-2+etch2 of shibboleth-sp. For the stable distribution (lenny), this problem has been fixed in version 1.3.1.dfsg1-3+lenny2 of shibboleth-sp, version 2.0.dfsg1-4+lenny2 of shibboleth-sp2 and version 2.0-2+lenny2 of opensaml2. For the unstable distribution (sid), this problem has been fixed in version 2.3+dfsg-1 of shibboleth-sp2, version 2.3-1 of opensaml2 and version 1.3.1-1 of xmltooling. We recommend that you upgrade your Shibboleth packages.