Critical: krb5 security update

Updated krb5 packages that fix multiple security issues are now available
for Red Hat Enterprise Linux 4.

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
/var/kerberos/krb5kdc/kdc.conf.

Red Hat would like to thank MIT for reporting these issues.

A double-free flaw was discovered in the GSSAPI library used by MIT
Kerberos. This flaw could possibly cause a crash of the application using
the GSSAPI library. (CVE-2007-5971)

All krb5 users are advised to update to these erratum packages which
contain backported fixes to correct these issues.

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/FAQ_58_10188

415351 - CVE-2007-5971 krb5: double free in gssapi lib
432620 - CVE-2008-0062 krb5: uninitialized pointer use in krb5kdc
432621 - CVE-2008-0063 krb5: possible leak of sensitive data from krb5kdc using krb4 request

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2007-5971
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0062
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2008-0063
http://www.redhat.com/security/updates/classification/#critical