Inconsistent interpretation of HTTP requests in Traefik - CVE-2026-71324
Published: August 21, 2026
Vulnerability identifier: #VU144546
CSH Severity: High
CVSS v4: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-71324
CWE-ID: CWE-444
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to poison cross-user HTTP responses and disclose sensitive information.
The vulnerability exists due to inconsistent interpretation of HTTP requests in Traefik\'s default reverse proxy shared backend keep-alive pool when forwarding HTTP/2 or HTTP/3 CONNECT requests with a body to an HTTP/1.1 upstream over a shared net/http.Transport. A remote attacker can send a specially crafted CONNECT request to poison cross-user HTTP responses and disclose sensitive information.
Exploitation requires an HTTP/2 or HTTP/3 frontend and an upstream that returns a keep-alive non-2xx response to the forwarded CONNECT request without draining the body.
Affected software
Traefik
How to mitigate CVE-2026-71324
Install security update from vendor's website.
Traefik - addressed in versions 2.11.53, 3.6.24, 3.7.9