Updated krb5 packages that fix multiple security issues are now available
for Red Hat Enterprise Linux 4.5 Extended Update Support.
This update has been rated as having critical security impact by the Red
Hat Security Response Team.
Kerberos is a network authentication system which allows clients and
servers to authenticate to each other through use of symmetric encryption
and a trusted third party, the KDC.
A flaw was found in the way the MIT Kerberos Authentication Service and Key
Distribution Center server (krb5kdc) handled Kerberos v4 protocol packets.
An unauthenticated remote attacker could use this flaw to crash the
krb5kdc daemon, disclose portions of its memory, or possibly execute
arbitrary code using malformed or truncated Kerberos v4 protocol
requests. (CVE-2008-0062, CVE-2008-0063)
This issue only affected krb5kdc with Kerberos v4 protocol compatibility
enabled, which is the default setting on Red Hat Enterprise Linux 4.
Kerberos v4 protocol support can be disabled by adding "v4_mode=none"
(without the quotes) to the "[kdcdefaults]" section of
Red Hat would like to thank MIT for reporting these issues.
All krb5 users are advised to update to these erratum packages which
contain backported fixes to correct these issues.