{"id":"CVE-2026-77803","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-77803","generatedAt":"2026-10-28T00:18:55.413Z","title":"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…","description":"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.","published":"2026-10-05T13:16:54.000Z","lastModified":"2026-10-06T18:16:56.000Z","status":"Awaiting Analysis","sourceIdentifier":"security@progress.com","cvss":{"version":"3.1","score":3.6,"severity":"LOW","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N"},"cwe":["CWE-444"],"affected":[],"epss":{"score":0.00097,"percentile":0.00717,"date":"2026-10-26","history":[{"date":"2026-10-06","score":0.00087,"percentile":0.00322}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.10%). Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-05T13:16:54.000Z","detail":{"score":"3.6","severity":"LOW","publishedAt":"2026-10-05T13:16:54.453Z"},"summary":"New CVE, low severity (CVSS 3.6)."}],"references":[{"url":"https://docs.telerik.com/fiddler/knowledge-base/kb-security-front-end-desynchronization-cve-2026-77803","source":"security@progress.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-77803","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}