Winter: Authenticated backend users can bypass Users controller permission checks

Summary

Winter CMS is a content management system built on the Laravel PHP framework. In versions prior to 1.2.13, the backend did not validate the handler name submitted through the form postback _handler POST field, allowing an authenticated backend user to invoke arbitrary controller methods, including protected, private, and action-prefixed ones. While AJAX requests validate that handler names match the on[A-Z][\w+]* pattern, the postback path passed the submitted _handler value straight to the handler dispatcher with no such check, so any controller that exposes a public action or conditionally relaxes its $requiredPermissions check could be reached, bypassing the roles and permissions system. The built-in Users controller was affected because it set $requiredPermissions to null for the myaccount action, letting any authenticated backend user invoke user-management methods such as update_onDelete and update_onManualPasswordReset without holding the backend.manage_users permission. This issue is fixed in version 1.2.13.

Timeline

1. Aug 26, 2026, 4:40 PM UTCCVE published
2. Aug 26, 2026, 7:07 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Aug 26, 2026, 7:08 PM UTCRecord last updated

Affected versions

• wintercms winter

  fixed in 1.2.13

• winter/wn-backend-modulePackagist

  fixed in 1.2.13

References 3