CVE-2026-75922 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.
Attackers can perform HTTP request smuggling by injecting CRLF sequences into PATH_INFO, allowing them to bypass proxy routing and access restricted upstream paths.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-75922?
CVE-2026-75922 is a medium-severity vulnerability, published on 23 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-75922?
How do I fix CVE-2026-75922?
No fix has been published for CVE-2026-75922 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-75922 being exploited?
There is no known exploitation of CVE-2026-75922 in the wild and no public exploit code.
Sources
Also known as GHSA-5xq5-hx4g-f5v6.