Launchpad.net

CVE 2011-1024

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.

See the CVE page on Mitre.org for more details.