mod/forum/post.php in Moodle 2.9.x before 2.9.1 does not consider the mod/forum:canposttomygroups capability before authorizing "Post a copy to all groups" actions, which allows remote authenticated users to bypass intended access restrictions by leveraging per-group authorization.
Severity
CVSS 3.0
4.3 medium
CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
EPSS
1.5% chance of exploitation in the next 30 days; higher than 74% of CVEs (scores of 2026-10-31)