/ 
Plack-1.0055
⭐ Starred 488 / Plack::Middleware::ContentLength
Security Advisories (1)
CVE-2026-115825 (2026-10-25)

HTTP::Server::PSGI versions before 1.0056 for Perl allow a single request to crash the server by declaring a large Content-Length. The request body is read with sysread() calls sized by the remaining Content-Length. Perl grows the read buffer to the requested length before any data arrives, so the server tries to allocate as much memory as the client declares. A remote attacker can send one request with a large Content-Length and a few body bytes, and perl exits with an out-of-memory error before the application is called. HTTP::Server::PSGI runs as a single process, so the server stays down until restarted.

NAME

Plack::Middleware::ContentLength - Adds Content-Length header automatically

SYNOPSIS

# in app.psgi

builder {
    enable "Plack::Middleware::ContentLength";
    $app;
}

# Or in Plack::Handler::*
$app = Plack::Middleware::ContentLength->wrap($app);

DESCRIPTION

Plack::Middleware::ContentLength is a middleware that automatically adds Content-Length header when it's appropriate i.e. the response has a content body with calculable size (array of chunks or a real filehandle).

This middleware can also be used as a library from PSGI server implementations to automatically set Content-Length rather than in the end user level.

AUTHOR

Tatsuhiko Miyagawa

SEE ALSO

Rack::ContentLength