pam_namespace.c in the pam_namespace module in Linux-PAM (aka pam) before 1.1.3 uses the environment of the invoking application or service during execution of the namespace.init script, which might allow local users to gain privileges by running a setuid program that relies on the pam_namespace PAM check, as demonstrated by the sudo program.
https://bugzilla.redhat.com/show_bug.cgi?id=643043
http://www.vupen.com/english/advisories/2011/0606
http://www.vmware.com/security/advisories/VMSA-2011-0004.html
http://www.securityfocus.com/archive/1/516909/100/0/threaded
http://www.redhat.com/support/errata/RHSA-2010-0891.html
http://www.redhat.com/support/errata/RHSA-2010-0819.html
http://www.mandriva.com/security/advisories?name=MDVSA-2010:220
http://security.gentoo.org/glsa/glsa-201206-31.xml
http://secunia.com/advisories/49711
http://lists.vmware.com/pipermail/security-announce/2011/000126.html