Multiple vulnerabilities have been reported in Kerberos, which can be exploited by malicious people to cause a DoS (Denial of Service).

1) A NULL-pointer dereference error in the "krb5_ldap_get_principal()" function can be exploited to crash the KDC daemon.

Successful exploitation of this vulnerability requires KDC to be configured to use a LDAP back end (not a default configuration).

This vulnerability is reported in krb5-1.9 and later only.

2) An assertion error in the "krb5_ldap_lockout_audit()" and "krb5_db2_lockout_audit()" functions can be exploited to crash the KDC daemon.

3) A NULL-pointer dereference error in the "lookup_lockout_policy()" function can be exploited to crash the KDC daemon.

Vulnerabilities #2 and #3 are reported in krb5-1.8 and later.

Solution
Apply patches (fixes are scheduled for the upcoming release of krb5-1.8.x and krb5-1.9.x).
Further details available to Secunia VIM customers

Provided and/or discovered by
1) The vendor credits Nalin Dahyabhai and Andrej Ota.
1) Independently reported by Kyle Moffett in a Debian bug report.
2) Reported by Mark Deneen in a Ubuntu bug report.
3) Reported by the vendor.

Changelog
Further details available to Secunia VIM customers

Original Advisory
MITKRB5-SA-2011-006:
http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2011-006.txt

Other references
Further details available to Secunia VIM customers

Deep Links
Links available to Secunia VIM customers