In Progress® Telerik® UI for .NET MAUI prior to version 16.0.0, an untrusted URL redirection vulnerability in the RadRichTextEditor hyperlink handling and the RadPdfViewer link annotation handling allows an unauthenticated attacker to launch arbitrary operating system protocol handlers with attacker-controlled arguments via a crafted document or PDF link with a non-allowlisted URI scheme that the user opens.
For RadPdfViewer, handle the LinkAnnotationTapped event, set Handled to true and launch only URIs with trusted schemes (http, https, mailto, tel). RadRichTextEditor has no equivalent event in the affected versions, so avoid loading documents from untrusted sources or upgrade to the fixed version.