CVE-2026-24687: 
C# vulnerability analysis and mitigation

Umbraco Forms is a form builder that integrates with the Umbraco content management system. It's possible for an authenticated backoffice-user to enumerate and traverse paths/files on the systems filesystem and read their contents, on Mac/Linux Umbraco installations using Forms. As Umbraco Cloud runs in a Windows environment, Cloud users aren't affected. This issue affects versions 16 and 17 of Umbraco Forms and is patched in 16.4.1 and 17.1.1. If upgrading is not immediately possible, users can mitigate this vulnerability by configuring a WAF or reverse proxy to block requests containing path traversal sequences (../, ..\) in the fileName parameter of the export endpoint, restricting network access to the Umbraco backoffice to trusted IP ranges, and/or blocking the /umbraco/forms/api/v1/export endpoint entirely if the export feature is not required. However, upgrading to the patched version is strongly recommended.