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 v4.0

6.3 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

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

EPSS

0.29% chance of exploitation in the next 30 days, 21th percentile

Published

2026-07-28

Proof-of-concept exploits (1)

• theopaid/HTTP-Request-Smuggling-via-Transfer-Encoding-Desynchronization-rouille-0★ · 2026-07-28

References

• CVE Record
• NVD entry

Related

• CVE-2023-27163
• CVE-2026-66729
• CVE-2026-66730
• CVE-2026-66731
• CVE-2026-66746
• CVE-2026-66748