CVE-2026-77803

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forwarding component. A request that contains both a Content-Length and a Transfer-Encoding header is forwarded with both headers present,...

CVE-2026-77802

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

EUVD-2026-92426

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forwarding component. A request that contains both a Content-Length and a Transfer-Encoding header is forwarded with both headers present,...

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-2026-77803 Front-end Desynchronization Vulnerability in Progress® Telerik® Fiddler® Classic

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forwarding component. A request that contains both a Content-Length and a Transfer-Encoding header is forwarded with both headers present,...

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...

CVE-2026-77802 HTTP Request Smuggling Vulnerability in Progress® Telerik® Fiddler® Classic

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

CVE-2026-77802 HTTP Request Smuggling Vulnerability in Progress® Telerik® Fiddler® Classic

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

EUVD-2026-92425

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

PT-2026-105987

Name of the Vulnerable Software and Affected Versions Progress Telerik Fiddler Classic for Windows versions prior to 6.0.20262.10021 Description HTTP request smuggling is possible in the proxy request forwarding component. This occurs when requests containing multiple Content-Length headers with...

CVE-2026-77803: Inconsistent Interpretation of HTTP Requests

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, front-end request desynchronization is possible in the proxy request forwarding component. A request that contains both a Content-Length and a Transfer-Encoding header is forwarded with both headers present,...

CVE-2026-77802: Inconsistent Interpretation of HTTP Requests

In Progress® Telerik® Fiddler® Classic for Windows, versions prior to v6.0.20262.10021, HTTP request smuggling is possible in the proxy request forwarding component. Requests containing multiple Content-Length headers with conflicting values are forwarded verbatim to the origin server, while...

PT-2026-105988

Name of the Vulnerable Software and Affected Versions Progress Telerik Fiddler Classic for Windows versions prior to 6.0.20262.10021 Description Front-end request desynchronization is possible in the proxy request forwarding component. When a request contains both Content-Length and...