Medium · published September 14, 2026
DotVVM is an open source MVVM framework for web applications. Prior to 4.2.11, 4.3.15, and 5.0.0-preview09-final, applications with configured file upload storage allow unauthenticated users to submit files directly to DotvvmFileUploadMiddleware without an X-DotVVM-UploadToken generated by the FileUpload component. An attacker can repeatedly upload files and fill application storage, causing denial of service. DotvvmConfiguration.Security.AuthorizeFileUpload can additionally restrict which users may upload files. This issue is fixed in versions 4.2.11, 4.3.15, and 5.0.0-preview09-final.