CVE-2026-54387

CRITICAL

Tinyproxy - HTTP Request Smuggling via CL/TE Desynchronization

Title source: cna
STIX 2.1

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.

References (4)

Core 4
Core References
Technical Description technical-description
Researcher Pull Request
https://github.com/tinyproxy/tinyproxy/issues/609
Issue Tracking issue-tracking
Maintainer Pull Request
https://github.com/tinyproxy/tinyproxy/pull/610

Scores

CVSS v3 9.1
EPSS 0.0039
EPSS Percentile 30.1%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact total

Details

CWE
CWE-444
Status published
Products (2)
tinyproxy/tinyproxy < 1.11.3
tinyproxy/tinyproxy ff45d3bf0e61d0f8ed97ab379d3047f04eb67521
Published Jun 17, 2026
Tracked Since Jun 18, 2026