CVE-2026-40561

Published May 3rd, 2026

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CVSS v3

5.3

MEDIUM

CVSS v2

N/A

Affected

PROJECT

Description

Starlet versions through 0.31 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starlet incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Transfer-Encoding must take precedence. An attacker could exploit this to smuggle malicious HTTP requests via a front-end reverse proxy.

kazuho/Starlet

a Plack Server, formerly known as Plack::Server::Standalone::Prefork::Server::Starter

GitHub