CVE-2026-54387

Critical

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.

SeverityCritical

CVSS9.1

Exploit probability—

ProductTinyproxy

PublishedJun 17, 2026

First seenJun 17, 2026

Weakness typeCWE-444CWE-444

How to fix

Patches

github.com/tinyproxy/tinyproxy/commit/ff45d3bf0e61d0f8ed97ab379d3047f04eb67521

Affected products

Product	Affected versions	Fixed in
tinyproxy tinyproxy	v ≤ 1.11.3	—

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.