In Progress® Telerik® UI for ASP.NET MVC versions `2012.2.710` through `2026.3.1015`, server-side filter processing does not properly validate descriptor types, null values, or stack state in FilterNodeVisitor and does not catch FilterParserException within the affected assembly. An unauthenticated remote attacker can exploit this if the application exposes an endpoint reachable without authentication that accepts crafted filter parameters. Affected requests can trigger uncaught cast, null-reference, or empty-stack exceptions and return HTTP 500. The report does not demonstrate worker-process termination or disruption of unrelated requests. The issue is fixed in version `2026.4.1111`.