CVE-2018-7169

Description

An issue was discovered in shadow 4.5. newgidmap (in shadow-utils) is setuid and allows an unprivileged user to be placed in a user namespace where setgroups(2) is permitted. This allows an attacker to remove themselves from a supplementary group, which may allow access to certain filesystem paths if the administrator has used "group blacklisting" (e.g., chmod g-rwx) to restrict access to paths. This flaw effectively reverts a security feature in the kernel (in particular, the /proc/self/setgroups knob) to prevent this sort of privilege escalation.

Weakness classification

• CWE-732: Incorrect Permission Assignment for Critical Resource

Primary references

• cve@mitre.org — Exploit, Issue Tracking, Third Party Advisory
• cve@mitre.org — Third Party Advisory
• af854a3a-2127-422b-91ae-364da2661108 — Exploit, Issue Tracking, Third Party Advisory
• af854a3a-2127-422b-91ae-364da2661108 — Third Party Advisory