Zeek versions before 8.0.9 contain a null pointer dereference vulnerability in the Kerberos protocol analyzer. This flaw allows unauthenticated remote attackers to crash the sensor by sending a specially crafted KRB_ERROR message with error-code 25 containing certain PA-DATA elements. The vulnerability arises from a parser and analyzer state mismatch that leads to dereferencing an uninitialized field, causing a crash via a single UDP or TCP packet to port 88 without authentication.