This indicates an attack attempt against a denial-of-service vulnerability in MIT's Kerberos KDC.
The vulnerability is caused by an error when the vulnerable software handles a specially crafted packet. It allows a remote attacker to cause a denial of service.
MIT Kerberos 5 1.7.1
MIT Kerberos 5 1.7
Denial of Service
Apply the patch released by the vendor. See the vendor's advisory for details: