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CVE-2026-40562                                       CPAN Security Group
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         CVE ID:  CVE-2026-40562
   Distribution:  Gazelle
       Versions:  through 0.49

       MetaCPAN:  https://metacpan.org/dist/Gazelle
       VCS Repo:  https://github.com/kazeburo/Gazelle

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

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.

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

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

References
----------
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

Timeline
--------
- 2026-04-12: Issue identified by CPANSec
- 2026-04-29: Issue reported to software maintainer

Credits
-------
CPANSec, finder