The kdc_handle_protected_negotiation function in the Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) 1.8.x, 1.9.x before 1.9.5, and 1.10.x before 1.10.3 attempts to calculate a checksum before verifying that the key type is appropriate for a checksum, which allows remote attackers to execute arbitrary code or cause a denial of service (uninitialized pointer free, heap memory corruption, and daemon crash) via a crafted AS-REQ request.
Improper Input Validation The product receives input or data, but it does
not validate or incorrectly validates that the input has the
properties that are required to process the data safely and
correctly.