Winter CMS has Stored Cross-site Scripting (XSS) in Asset Manager

Impact

Affected versions of Winter CMS allow users with access to the CMS Asset Manager were able to upload SVGs without automatic sanitization.

To actively exploit this security issue, an attacker would need access to the Backend with a user account with the following permission: cms.manage_assets

The Winter CMS maintainers strongly recommend that the cms.manage_assets permission only be reserved to trusted administrators and developers in general.

Patches

Sanitization of SVG assets is now applied automatically when uploading through the CMS Asset Manager.

This security issue has been fixed as of https://github.com/wintercms/winter/commit/8a7f74b004fcd19721764fc63af0cdb339d9fb65.

Workarounds

If users cannot upgrade, they may apply commit https://github.com/wintercms/winter/commit/8a7f74b004fcd19721764fc63af0cdb339d9fb65 to their Winter CMS installation manually to resolve this issue.