OpenPAM Nummularia 9.2 through 10.0 does not properly handle the error reported when an include directive refers to a policy that does not exist, which causes the loaded policy chain to no be discarded and allows context-dependent attackers to bypass authentication via a login (1) without a password or (2) with an incorrect password.
http://www.securitytracker.com/id/1030330
http://www.securityfocus.com/bid/67808
http://www.openpam.org/browser/openpam/trunk/HISTORY
http://www.freebsd.org/security/advisories/FreeBSD-SA-14:13.pam.asc