Multiple vulnerabilities has been identified and fixed in openldap:

chain.c in back-ldap in OpenLDAP 2.4.x before 2.4.24,
when a master-slave configuration with a chain overlay and
ppolicy_forward_updates (aka authentication-failure forwarding) is
used, allows remote authenticated users to bypass external-program
authentication by sending an invalid password to a slave server
(CVE-2011-1024).

modrdn.c in slapd in OpenLDAP 2.4.x before 2.4.24 allows remote
attackers to cause a denial of service (daemon crash) via a relative
Distinguished Name (DN) modification request (aka MODRDN operation)
that contains an empty value for the OldDN field (CVE-2011-1081).

Packages for 2009.0 are provided as of the Extended Maintenance
Program. Please visit this link to learn more:
http://store.mandriva.com/product_info.php?cPath=149&products_id=490

The updated packages have been patched to correct these issues.