CVE-2026-77803
LOW
3,6
Source: [email protected]
Attack Vector: local
Attack Complexity: high
Privileges Required: low
User Interaction: none
Scope: unchanged
Confidentiality: low
Integrity: low
Availability: none
Description
AI Translation Available
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, while Fiddler frames the body using Transfer-Encoding only. The remaining bytes on the reused client connection are then parsed as a separate pipelined request, so a local threat actor with low privileges can cause a single malformed request to be split into two requests forwarded to the origin server and receive an additional smuggled response, without requiring a vulnerable server.
444
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
IncompleteCommon Consequences
Security Scopes Affected:
Integrity
Non-Repudiation
Access Control
Potential Impacts:
Unexpected State
Hide Activities
Bypass Protection Mechanism
Applicable Platforms
Technologies:
Web Based, Web Server
https://docs.telerik.com/fiddler/knowledge-base/kb-security-front-end-desynchro…