The winbind_name_list_to_sid_string_list function in nsswitch/pam_winbind.c in Samba through 4.1.2 handles invalid require_membership_of group names by accepting authentication by any user, which allows remote authenticated users to bypass intended access restrictions in opportunistic circumstances by leveraging an administrator's pam_winbind configuration-file mistake.

References

• https://nvd.nist.gov/vuln/detail/CVE-2012-6150
• https://bugzilla.redhat.com/show_bug.cgi?id=1036897
• https://bugzilla.samba.org/show_bug.cgi?id=10300
• https://lists.samba.org/archive/samba-technical/2012-June/084593.html
• https://lists.samba.org/archive/samba-technical/2013-November/096411.html
• http://lists.fedoraproject.org/pipermail/package-announce/2014-August/136864.html
• http://lists.fedoraproject.org/pipermail/package-announce/2014-June/134717.html
• http://lists.opensuse.org/opensuse-security-announce/2014-01/msg00002.html
• http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00047.html
• http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00048.html
• http://lists.opensuse.org/opensuse-updates/2013-12/msg00088.html
• http://lists.opensuse.org/opensuse-updates/2014-03/msg00063.html
• http://marc.info/?l=bugtraq&m=141660010015249&w=2
• http://openwall.com/lists/oss-security/2013/12/03/5
• http://rhn.redhat.com/errata/RHSA-2014-0330.html
• http://security.gentoo.org/glsa/glsa-201502-15.xml
• http://www.mandriva.com/security/advisories?name=MDVSA-2013:299
• http://www.ubuntu.com/usn/USN-2054-1