/ 
Plack-1.0053
⭐ Starred 488 / Plack::Middleware::Conditional
Security Advisories (1)
CVE-2026-7381 (2026-04-29)

Plack::Middleware::XSendfile versions through 1.0053 for Perl can allow client-controlled path rewriting. Plack::Middleware::XSendfile allows the variation setting (sendfile type) to be set by the client via the X-Sendfile-Type header, if it is not considered in the middleware constructor or the Plack environment. A malicious client can set the X-Sendfile-Type header to "X-Accel-Redirect" to services running behind nginx reverse proxies, and then set the X-Accel-Mapping to map the path to an arbitrary file on the server. Since 1.0053, Plack::Middleware::XSendfile is deprecated and will be removed from future releases of Plack. This is similar to CVE-2025-61780 for Rack::Sendfile, although Plack::Middleware::XSendfile has some mitigations that disallow regular expressions to be used in the mapping, and only apply the mapping for the "X-Accel-Redirect" type.

NAME

Plack::Middleware::Conditional - Conditional wrapper for Plack middleware

SYNOPSIS

use Plack::Builder;

builder {
    enable_if { $_[0]->{REMOTE_ADDR} eq '127.0.0.1' } 'StackTrace', force => 1;
    $app;
};

# or using the OO interface:
$app = Plack::Middleware::Conditional->wrap(
    $app,
    condition  => sub { $_[0]->{REMOTE_ADDR} eq '127.0.0.1' },
    builder => sub { Plack::Middleware::StackTrace->wrap($_[0], force => 1) },
);

DESCRIPTION

Plack::Middleware::Conditional is a piece of meta-middleware, to run a specific middleware component under runtime conditions. The goal of this middleware is to avoid baking runtime configuration options in individual middleware components, and rather share them as another middleware component.

EXAMPLES

Note that some of the middleware component names are just made up for the explanation and might not exist.

# Minify JavaScript if the browser is Firefox
enable_if { $_[0]->{HTTP_USER_AGENT} =~ /Firefox/ } 'JavaScriptMinifier';

# Enable Stacktrace when being accessed from the local network
enable_if { $_[0]->{REMOTE_ADDR} =~ /^10\.0\.1\.*/ } 'StackTrace';

# Work with other conditional setter middleware:
# Transcode Jpeg on the fly for mobile clients
builder {
    enable 'MobileDetector';
    enable_if { $_[0]->{'plack.mobile_detected'} }
      'TranscodeJpeg', max_size => 30_000;
    $app;
};

Note that in the last example MobileDetector should come first because the conditional check runs in pre-run conditions, which is from outer to inner: that is, from the top to the bottom in the Builder DSL code.

AUTHOR

Tatsuhiko Miyagawa

Steve Cook

SEE ALSO

Plack::Builder