HTTP Request Smuggling Vulnerability in Reverse::Proxy by Perl
CVE-2026-75922
What is CVE-2026-75922?
The Reverse::Proxy module for Perl prior to version 0.04 is susceptible to HTTP request smuggling attacks. This vulnerability occurs due to the handling of the client URL's PATH_INFO, which is sent to the application in a percent-decoded format. When a client sends a specially crafted URL containing %XX sequences, these characters are treated as raw bytes by the proxy. As a result, malicious payloads can be injected into the request line. When the proxy constructs the upstream request, it fails to properly encode the path, allowing attackers to manipulate the request line. Notably, characters such as %0d%0a can introduce CRLF sequences, causing the upstream server to interpret subsequent headers as part of a new request. This can potentially lead to unauthorized requests being processed by the server, exposing critical internal resources and compromising the integrity of the system.