Kerberos is a network authentication system which allows clients and servers to authenticate to each other using symmetric encryption and a trusted third-party, the Key Distribution Center . A NULL pointer dereference flaw was found in the way the MIT Kerberos KDC processed certain TGS requests. A remote, authenticated attacker could use this flaw to crash the KDC via a specially-crafted TGS request. All krb5 users should upgrade to these updated packages, which contain a backported patch to correct this issue. After installing the updated packages, the krb5kdc daemon will be restarted automatically.