/ 
Plack-1.0055
⭐ Starred 488 / Plack::Middleware::LighttpdScriptNameFix
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::LighttpdScriptNameFix - fixes wrong SCRIPT_NAME and PATH_INFO that lighttpd sets

SYNOPSIS

# in your app.psgi
use Plack::Builder;

builder {
  enable "LighttpdScriptNameFix";
  $app;
};

# Or from the command line
plackup -s FCGI -e 'enable "LighttpdScriptNameFix"' /path/to/app.psgi

DESCRIPTION

This middleware fixes wrong SCRIPT_NAME and PATH_INFO set by lighttpd when you mount your app under the root path ("/"). If you use lighttpd 1.4.23 or later you can instead enable fix-root-scriptname flag inside fastcgi.server instead of using this middleware.

CONFIGURATION

script_name

Even with fix-root-scriptname, lighttpd still sets weird SCRIPT_NAME and PATH_INFO if you mount your application at "" or something that ends with /. Setting script_name option tells the middleware how to reconstruct the new correct SCRIPT_NAME and PATH_INFO.

If you mount the app under /something/, you should set:

enable "LighttpdScriptNameFix", script_name => "/something";

and when a request for /something/a/b?param=1 comes, SCRIPT_NAME becomes /something and PATH_INFO becomes /a/b.

script_name option is set to empty by default, which means all the request path is set to PATH_INFO and it behaves like your fastcgi application is mounted in the root path.

AUTHORS

Yury Zavarin

Tatsuhiko Miyagawa

SEE ALSO

Plack::Handler::FCGI http://github.com/plack/Plack/issues#issue/68 https://redmine.lighttpd.net/issues/729