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.
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
Source: MITRE
Published: 2017-02-06
Updated: 2019-10-03
Type: NVD-CWE-noinfo
Base Score: 3.6
Vector: AV:L/AC:L/Au:N/C:P/I:P/A:N
Impact Score: 4.9
Exploitability Score: 3.9
Severity: LOW
Base Score: 4.4
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
Impact Score: 2.5
Exploitability Score: 1.8
Severity: MEDIUM