The Key Distribution Center (KDC) in Kerberos 5 (krb5) 1.2.7 and earlier allows remote, authenticated attackers to cause a denial of service (crash) on KDCs within the same realm using a certain protocol request that causes the KDC to corrupt its heap (aka "buffer underrun").
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A4430
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A2536
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A244
http://www.securityfocus.com/bid/7185
http://www.securityfocus.com/archive/1/316960/30/25250/threaded
http://www.redhat.com/support/errata/RHSA-2003-091.html
http://www.redhat.com/support/errata/RHSA-2003-052.html
http://www.redhat.com/support/errata/RHSA-2003-051.html
http://www.debian.org/security/2003/dsa-266
http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2003-005-buf.txt
http://sunsolve.sun.com/search/document.do?assetkey=1-26-54042-1