Craft CMS Vulnerable to Stored XSS via User Group Name in User Permissions Page

## Summary A stored XSS vulnerability exists in the User Permissions page. The User Group name is rendered without proper HTML escaping in the permissions section, allowing an attacker to execute arbitrary JavaScript when another user views or edits a user's permissions. > [!NOTE] > This is a separate vulnerability from the previously reported "[Stored XSS via User Group Name in User Settings Page](https://github.com/craftcms/cms/security/advisories/GHSA-2423-8xxj-wc3g)" and "[Multiple Stored XSS in User Group Edit Page](https://github.com/craftcms/cms/security/advisories/GHSA-vx7g-xw92-g4xj)". This affects a different sink: the individual user's permissions page. ## Proof of Concept ### Required Permissions - Admin access - `allowAdminChanges` is enabled in production, which is against our [security recommendations](https://craftcms.com/knowledge-base/securing-craft). ### Steps to Reproduce 1. Log in to the control panel as an admin 2. Navigate to **Settings → Users → User Groups** 3. Create or edit a user group and set the **Name** field to: ```html <img src=x onerror="alert('XSS')" hidden> ``` 4. Save the user group 5. Navigate to **Users** and edit any user (`/admin/users/{id}`) 6. Click on the **Permissions** tab 7. XSS executes ## Mitigation Sanitize user group names when rendering in the user permissions template. ## References https://github.com/craftcms/cms-ghsa-4mgv-366x-qxvx/pull/2