CVE-2026-35445 Winter: Authenticated backend users can bypass Users controller permission checks

What is CVE-2026-35445?

CVE-2026-35445 is a high-severity vulnerability in wintercms winter, published on 26 Aug 2026.

Official description

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.

Weakness: CWE-285

Which versions are affected by CVE-2026-35445?

2 open source packages ship an affected version, including winter/wn-backend-module.

How do I fix CVE-2026-35445?

Upgrade winter/wn-backend-module to 1.2.13 or later.

Is CVE-2026-35445 being exploited?

There is no known exploitation of CVE-2026-35445 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-j5jq-cr68-v2xx.