CVE-2026-54388: Tinyproxy

Critical severity, CVSS 9.1. EPSS: 0.7% chance of exploitation in the next 30 days.

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.

Affected products

• Tinyproxy Tinyproxy: up to and including 1.11.3

Published 2026-06-17. Last modified 2026-07-14.