CVE-2026-40562 PUBLISHED

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.

Migrate to Starman version 0.4018 or newer which has fixed the issue. Or apply the patch.

• CPANSec finder

• https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3
• https://security.metacpan.org/patches/G/Gazelle/0.49/CVE-2026-40562-r1.patch

• CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') CWE

• CAPEC-33 HTTP Request Smuggling