The _unix_run_helper_binary function in the pam_unix module in Linux-PAM (aka pam) before 1.2.1, when unable to directly access passwords, allows local users to enumerate usernames or cause a denial of service (hang) via a large password.
https://security.gentoo.org/glsa/201605-05
https://bugzilla.redhat.com/show_bug.cgi?id=1228571
http://www.ubuntu.com/usn/USN-2935-3
http://www.ubuntu.com/usn/USN-2935-2
http://www.ubuntu.com/usn/USN-2935-1
http://www.securityfocus.com/bid/75428
http://www.oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html
http://www.openwall.com/lists/oss-security/2015/06/25/13
http://rhn.redhat.com/errata/RHSA-2015-1640.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-June/161249.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-July/161350.html