The process_as_req function in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.10.x before 1.10.3 does not initialize a certain structure member, which allows remote attackers to cause a denial of service (uninitialized pointer dereference and daemon crash) or possibly execute arbitrary code via a malformed AS-REQ request.
http://www.debian.org/security/2012/dsa-2518
http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2012-001.txt
http://lists.opensuse.org/opensuse-updates/2012-08/msg00016.html