CVE-2026-67181

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.

CVSS 4.0

6.3CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS 3.1

5.4CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:L

EPSS

0.4% chance of exploitation in the next 30 days; higher than 35% of CVEs (scores of 2026-10-25)

CWE

CWE-444

Published

2026-07-28

Modified

2026-10-24

Record from

the NVD, synced 2026-10-24

References

• https://github.com/theopaid/HTTP-Request-Smuggling-via-Transfer-Encoding-Desynchronization-rouille-
• https://www.vulncheck.com/advisories/rouille-http-request-smuggling-via-proxy-transfer-encoding-header

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