Vulnerability Description
Tinyproxy through 1.11.3, fixed in commit ff45d3b, fails to reconcile conflicting Content-Length and Transfer-Encoding: chunked headers, forwarding both verbatim to the backend while using Content-Length to determine how many request body bytes to consume. Remote attackers can desynchronize the proxy and backend parser state, allowing injection of arbitrary HTTP requests to the backend to enable cache poisoning, access control bypass, and request hijacking.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/tinyproxy/tinyproxy/commit/ff45d3bf0e61d0f8ed97ab379d3047f04e
- https://github.com/tinyproxy/tinyproxy/issues/609
- https://github.com/tinyproxy/tinyproxy/pull/610
- https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-cl-te-
FAQ
What is CVE-2026-54387?
CVE-2026-54387 is a vulnerability with a CVSS score of 9.1 (CRITICAL). Tinyproxy through 1.11.3, fixed in commit ff45d3b, fails to reconcile conflicting Content-Length and Transfer-Encoding: chunked headers, forwarding both verbatim to the backend while using Content-Len...
How severe is CVE-2026-54387?
CVE-2026-54387 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-54387?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.