CVE-2026-41128
Received Received - Intake

Authorization Bypass in Craft CMS Allows Arbitrary User Group Removal

Publication date: 2026-04-22

Last updated on: 2026-04-22

Assigner: GitHub, Inc.

Description
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.

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Meta Information

Published
2026-04-22
Last Modified
2026-04-22
Generated
2026-07-06
AI Q&A
2026-04-22
EPSS Evaluated
2026-07-05
NVD
CVE-2026-41128

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
craftcms craft_cms From 5.6.0 (inc) to 5.9.14 (inc)
craftcms craft_cms 5.9.15

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-862 The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

Attack-Flow Graph

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Executive Summary

This vulnerability exists in Craft CMS versions 5.6.0 through 5.9.14. It allows a user who only has the 'viewUsers' permission to remove any user from all user groups. The issue arises because the endpoint actionSavePermissions() does not properly check authorization when removing users from groups. While adding users to groups requires proper authorization, removing users does not, so submitting an empty 'groups' value effectively removes all group memberships for a user. This flaw was fixed in version 5.9.15.

Impact Analysis

This vulnerability can impact you by allowing users with minimal permissions (only 'viewUsers') to remove other users from all their user groups. This could lead to unauthorized changes in user roles and permissions, potentially disrupting access controls and security policies within the CMS. It may result in users losing access to resources or privileges they should have, or it could be exploited to weaken the system's security posture.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade Craft CMS to version 5.9.15 or later, where the issue has been patched.

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