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 . Multiple checksum validation flaws were discovered in the MIT Kerberos implementation. A remote attacker could use these flaws to tamper with certain Kerberos protocol packets and, possibly, bypass authentication mechanisms in certain configurations using Single-use Authentication Mechanisms. Red Hat would like to thank the MIT Kerberos Team for reporting these issues. All krb5 users should upgrade to these updated packages, which contain a backported patch to correct these issues. After installing the updated packages, the krb5kdc daemon will be restarted automatically.