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.
Plack::Middleware::Session::Simple versions before 0.05 for Perl generates session ids insecurely.
The default session id generator returns a SHA-1 hash seeded with the built-in rand function, the epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage.
Predictable session ids could allow an attacker to gain access to systems.
Plack::Middleware::Session::Simple is intended to be compatible with Plack::Middleware::Session, which had a similar security issue CVE-2025-40923.