CVE-2026-67181 Rouille 0.3.3 - 3.6.2 HTTP Request Smuggling via proxy Transfer-Encoding Header
Remote attackers can desynchronize HTTP message boundaries in Rouille's proxy implementation, potentially bypassing security controls or modifying data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-67181?
CVE-2026-67181 is a medium-severity vulnerability in tomaka rouille, published on 28 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Rouille 0.3.3 through 3.6.2 contains an HTTP request smuggling vulnerability that allows remote attackers to desynchronize HTTP message boundaries by exploiting improper header forwarding in the proxy implementation. The proxy in src/proxy.rs forwards the client's Transfer-Encoding header to upstream backends unchanged while transmitting a body already de-chunked by tiny_http, enabling CL.TE desynchronization attacks where attackers control where the backend believes the request body ends.
Weakness: CWE-444
Which versions are affected by CVE-2026-67181?
How do I fix CVE-2026-67181?
Upgrade to a fixed version.
Is CVE-2026-67181 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67181 exists.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as DEBIAN-CVE-2026-67181, GHSA-fgf8-ph7p-m275.