CVE-2026-40562: Kazeburo Gazelle

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

Gazelle versions through 0.49 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Gazelle 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

• Kazeburo Gazelle: before 0.50 (fixed in 0.50)

Published 2026-05-06. Last modified 2026-06-17.