EUVD-2026-92428

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode...

CVE-2026-77805 Weak Executable Signature Verification Vulnerability in Progress® Telerik® Fiddler® Classic

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, the integrity check applied to the external helper tools launched by the application is insufficient. Before executing a helper tool, the application only verifies that the file carries a valid Authenticode...

EUVD-2026-92427

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, a time-of-check time-of-use TOCTOU race condition exists in the installation of the HTTPS interception root certificate into the Local Computer certificate store. Fiddler writes the certificate to a temporary...

CVE-2026-77803

Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021 , contains a front-end request desynchronization vulnerability in the proxy request forwarding component. The root cause is that the software forwards requests containing both Content-Length and Transfer-Encoding ...

CVE-2026-77802

Progress Telerik Fiddler Classic for Windows versions prior to v6.0.20262.10021 are vulnerable to HTTP request smuggling in the proxy request forwarding component. The issue arises because the software forwards requests with multiple conflicting Content-Length headers verbatim, while only using t...