The spnego_gss_accept_sec_context function in lib/gssapi/spnego/spnego_mech.c in the SPNEGO GSS-API functionality in MIT Kerberos 5 (aka krb5) 1.7 before 1.7.2 and 1.8 before 1.8.1 allows remote attackers to cause a denial of service (assertion failure and daemon crash) via an invalid packet that triggers incorrect preparation of an error token.
https://bugzilla.redhat.com/show_bug.cgi?id=566258
http://www.ubuntu.com/usn/USN-916-1
http://www.securityfocus.com/bid/38904
http://www.securityfocus.com/archive/1/510281/100/0/threaded
http://www.kb.cert.org/vuls/id/839413
http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2010-002.txt