by Kastro
Paper/Archive/CVE-2026-54387

CVE-2026-54387

tinyproxy tinyproxy — Tinyproxy - HTTP Request Smuggling via CL/TE Desynchronization

EPSS 0.4%CVSS 9.3
critical.is priorityof 100
36
CVSS 9.3 (CNA)9.3 / 10 × 3027.9Not in CISA KEV+300.0EPSS percentile 38.1.381 × 207.6No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
tinyproxy≤ 1.11.3ff45d3bf0e61d0f8ed97ab379d3047f04eb67521CNA

Scores by source

VulnCheck (CNA)9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
VulnCheck (CNA)9.1CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refgithub.com/tinyproxy/tinyproxy/issues/609refgithub.com/tinyproxy/tinyproxy/pull/610patchgithub.com/tinyproxy/tinyproxy/commit/ff45d3bf0e61d0f8ed97ab379d3047f04eb67521writeupvulncheck.com/advisories/tinyproxy-http-request-smuggling-via-cl-te-desynchronization