CVE-2026-54388criticalCWE-444

CVE-2026-54388: critical vulnerability in tinyproxy

Tinyproxy - HTTP Request Smuggling via Duplicate Content-Length Headers

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28Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 9.3epss 0.4%
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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Affected products
tinyproxy · tinyproxy
Related CVEs — tinyproxy

In the same product, most dangerous first.

CVE-2026-3945HIGHtinyproxy Integer Overflow in HTTP Chunked Transfer-Encoding Parser Leading to Denial of ServiceEPSS 0.6%CVE-2026-54387CRITICALTinyproxy - HTTP Request Smuggling via CL/TE DesynchronizationEPSS 0.4%CVE-2026-55202HIGHTinyproxy - Stathost Detection Bypass via Host Header ManipulationEPSS 0.4%CVE-2026-125371MEDIUMTinyproxy through 1.11.3 Hostname ACL Allow-List Bypass via Suffix MatchEPSS —