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CVE-2026-75922: Reverse-Proxy

Severity

0 (N/A)

Affected versions

0 through before 0.04

Fixed version

0.04

Patch status

Patched

Published

2026-08-23T19:16:28.930

Modified

2026-08-23T19:16:28.930

Why it matters

This matters because the affected product may allow code execution. Prioritize systems that are internet-facing or have privileged access to other infrastructure.

Recommended admin actions

• Review during normal vulnerability triage unless the affected system is internet-facing or business-critical.
• Compare installed versions against the affected version range in the advisory.
• Review logs for suspicious activity related to the affected application or component.

Technical summary

Reverse::Proxy versions before 0.04 for Perl allow HTTP request smuggling via a percent-decoded PATH_INFO written unencoded to the upstream request line. PSGI hands PATH_INFO to an application percent-decoded, so a %XX sequence in the client URL has become a raw byte by the time the proxy sees it. The proxy appends that byte string to the upstream base URL, and for an Upgrade tunnel writes it into a request line it serializes itself, re-encoding nothing in either path. The HTTP client that sends the resulting URL does not validate the target either. A path containing %0d%0a therefore arrives at the upstream as a CRLF that ends the request line, and a decoded space, '?' or '#' truncates it the same way. Everything the client writes after the CRLF is read by the upstream as a second request. On the buffered path it arrives on a keep-alive connection the proxy pools and reuses for other clients. Its method, path and headers are all chosen by the client, and the upstream attributes it to the proxy, so it reaches upstream paths that the proxy's own routing does not expose.

View the official NVD record for CVE-2026-75922

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.