Vulnerability Description
Tinyproxy through 1.11.3, fixed in commit 364cdb6, fails to reject requests containing multiple Content-Length headers with differing values, forwarding all duplicate headers to the backend while using the first value 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/364cdb67e0ea00a8e4a7037e2693e0711e
- https://github.com/tinyproxy/tinyproxy/issues/609
- https://github.com/tinyproxy/tinyproxy/pull/610
- https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-duplic
- https://github.com/tinyproxy/tinyproxy/issues/609
FAQ
What is CVE-2026-54388?
CVE-2026-54388 is a vulnerability with a CVSS score of 9.1 (CRITICAL). Tinyproxy through 1.11.3, fixed in commit 364cdb6, fails to reject requests containing multiple Content-Length headers with differing values, forwarding all duplicate headers to the backend while usin...
How severe is CVE-2026-54388?
CVE-2026-54388 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-2026-54388?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.