The SELinux version of PAM before 0.78 r3 allows local users to perform brute force password guessing attacks via unix_chkpwd, which does not log failed guesses or delay its responses.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10193
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=168181
http://www.vupen.com/english/advisories/2005/2227
http://www.securityfocus.com/bid/15217
http://www.redhat.com/support/errata/RHSA-2005-805.html
http://www.gentoo.org/security/en/glsa/glsa-200510-22.xml
http://securitytracker.com/id?1015111
http://secunia.com/advisories/17365
http://secunia.com/advisories/17352
http://secunia.com/advisories/17350
http://secunia.com/advisories/17346
http://cvs.sourceforge.net/viewcvs.py/pam/Linux-PAM/NEWS?rev=1.6&view=markup