Updated krb5 packages that fix one security issue are now available for Red Hat Enterprise Linux 6. The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System base score, which gives a detailed severity rating, is available from the CVE link in the References section. 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.