Description

The Linux kernel through 3.17.4 does not properly restrict dropping of supplemental group memberships in certain namespace scenarios, which allows local users to bypass intended file permissions by leveraging a POSIX ACL containing an entry for the group category that is more restrictive than the entry for the other category, aka a "negative groups" issue, related to kernel/groups.c, kernel/uid16.c, and kernel/user_namespace.c.

References

http://lists.fedoraproject.org/pipermail/package-announce/2015-January/147864.html

http://lists.fedoraproject.org/pipermail/package-announce/2015-January/147973.html

http://thread.gmane.org/gmane.linux.man/7385/

http://www.mandriva.com/security/advisories?name=MDVSA-2015:058

http://www.openwall.com/lists/oss-security/2014/11/20/4

http://www.securityfocus.com/bid/71154

http://www.ubuntu.com/usn/USN-2515-1

http://www.ubuntu.com/usn/USN-2516-1

http://www.ubuntu.com/usn/USN-2517-1

http://www.ubuntu.com/usn/USN-2518-1

Details

Risk Information

CVSS v2