Craft CMS is a content management system (CMS). In versions 5.6.0 through 5.9.14, the `actionSavePermissions()` endpoint allows a user with only `viewUsers` permission to remove arbitrary users from all user groups. While `_saveUserGroups()` enforces per-group authorization for additions, it performs no equivalent authorization check for removals, so submitting an empty `groups` value removes all existing group memberships. Version 5.9.15 contains a patch.
https://github.com/craftcms/cms/security/advisories/GHSA-jq2f-59pj-p3m3
https://github.com/craftcms/cms/commit/b135384808ad43fcf8836a9dd9b877fb0087bc27
Published: 2026-04-22
Updated: 2026-04-22
Base Score: 5.5
Vector: CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:N
Severity: Medium
Base Score: 6.5
Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Severity: Medium
EPSS: 0.00031