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 important 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. Description 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 . The Public Key Cryptography for Initial Authentication in Kerberos capability provides support for using public-key authentication with Kerberos. A double-free flaw was found in the way the MIT Kerberos KDC handled initial authentication requests , when the KDC was configured to provide the PKINIT capability. A remote attacker could use this flaw to cause the KDC daemon to abort by using a specially-crafted AS-REQ 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.