What’s Vulnerable › Vulnerabilities

CVE-2026-40562: Gazelle versions through 0.49 for Perl allows HTTP Request Smuggling via Improper Header Precedence

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-06 · updated 2026-10-26
• Weakness: CWE-444

Description

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

How to fix

Upgrade to a fixed version: KAZEBURO Gazelle 0.50. Check the vendor advisory for mitigations.

References

• https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3
• https://metacpan.org/release/KAZEBURO/Gazelle-0.50/changes
• https://security.metacpan.org/patches/G/Gazelle/0.49/CVE-2026-40562-r1.patch
• http://www.openwall.com/lists/oss-security/2026/05/06/7

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