CVE-2026-40560: Miyagawa Starman

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starman 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.

Affected products

• Miyagawa Starman: before 0.4018 (fixed in 0.4018)

Published 2026-04-29. Last modified 2026-07-24.