CVE-2026-32639 Winter: Broken access control in `Cms\Controllers\Index` allows cross-template actions and unauthorized asset uploads
Authenticated backend users with limited CMS permissions can bypass authorization checks to modify unauthorized templates and upload files.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-32639?
CVE-2026-32639 is a medium-severity missing authorization vulnerability in wintercms winter, published on 26 Aug 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Winter CMS is a content management system built on the Laravel PHP framework. In versions up to and including 1.2.12, the CMS section's Theme Editor AJAX handlers did not enforce per-template-type permission checks, allowing a backend user with any single CMS permission to act on template types outside their authorized scope. The CMS controller gated access to the section as a whole using OR-logic across its five permissions, but individual handlers such as onSave(), onDelete(), and onDeleteTemplates() did not verify that the user held the specific permission for the requested template type, so a user with only cms.manage_pages could craft AJAX requests to delete layouts, modify partials, or read content files. Separately, the AssetList widget was registered for any user who passed the controller gate regardless of the cms.manage_assets permission, and its onUpload() handler omitted the theme-validation call present on the other mutating handlers, permitting unauthorized file uploads into the active theme's asset directory. Exploitation requires an authenticated backend account holding at least one of the CMS Theme Editor permissions. This issue is fixed in version 1.2.13.
Weakness: CWE-289
Which versions are affected by CVE-2026-32639?
2 open source packages ship an affected version, including winter/wn-cms-module.
| Package | Affected | Fixed in |
|---|---|---|
winter/wn-cms-module Packagist | All versions | 1.2.13 |
winter/wn-cms-module Packagist | All versions | 1.2.13 |
How do I fix CVE-2026-32639?
Upgrade winter/wn-cms-module to 1.2.13 or later.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-32639 being exploited?
There is no known exploitation of CVE-2026-32639 in the wild and no public exploit code.
Sources
Also known as GHSA-5c4f-9pq9-6c77.