This indicates an attack attempt to exploit a Denial of Service Vulnerability in Heimdal.
The vulnerability is due to an error in the vulnerable application when handling a maliciously crafted request. An attacker can exploit this to cause a denial of service condition on the affected machine via a crafted request.
Heimdal prior to 7.5.0
Denial of Service: Remote attackers can crash vulnerable systems.
Apply the most recent upgrade or patch from the vendor: