Description

The simple_set_acl function in fs/posix_acl.c in the Linux kernel before 4.9.6 preserves the setgid bit during a setxattr call involving a tmpfs filesystem, which allows local users to gain group privileges by leveraging the existence of a setgid program with restrictions on execute permissions. NOTE: this vulnerability exists because of an incomplete fix for CVE-2016-7097.

References

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=497de07d89c1410d76a15bec2bb41f24a2a89f31

http://www.debian.org/security/2017/dsa-3791

http://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.6

http://www.openwall.com/lists/oss-security/2017/01/21/3

http://www.securityfocus.com/bid/95717

http://www.securitytracker.com/id/1038053

https://bugzilla.redhat.com/show_bug.cgi?id=1416126

https://github.com/torvalds/linux/commit/497de07d89c1410d76a15bec2bb41f24a2a89f31

Details

Risk Information

CVSS v2

CVSS v3