CVE-2026-77803
CVE.org · Published
- Record status
- Published
- Identifier year (not publication year)
- 2026
- Source publication
- Source updated
- Imported by cveboard
- Source snapshot
- cve_2026-10-24_midnight_baseline ·
CNA source text (English)
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, 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.
Scoped product and version facts
Fix information unknown; no fixed version is derived here. Missing information does not prove that no fix exists.
Exploitation unknown; this catalogue does not assess exploitation.
Progress® Telerik® Fiddler® Classic
- Vendor
- Progress Software
- Product
- Progress® Telerik® Fiddler® Classic
- Platforms
- Windows
- Default status
unaffected
| Version (version) | Status (status) | Version scheme (versionType) | Exclusive end (lessThan) | Inclusive end (lessThanOrEqual) | Status changes (at → status) |
|---|---|---|---|---|---|
| 1.0.0 | affected | custom | 6.0.20262.10021 | Unavailable | None listed |