CVE-2026-71324 Traefik: Cross-user response poisoning via proxied CONNECT on Traefik's shared backend keep-alive pool
An unauthenticated attacker can poison responses to other clients via HTTP CONNECT desynchronization in Traefik's shared connection pool, leaking private 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-2026-71324?
CVE-2026-71324 is a high-severity vulnerability in Traefik Traefik, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.53, 3.6.24, and 3.7.9, Traefik's default HTTP reverse proxy forwards a plain HTTP/2 or HTTP/3 CONNECT request and its body to an HTTP/1.1 upstream through a shared net/http.Transport. When the upstream answers the CONNECT with a keep-alive non-2xx response and does not drain the body, Traefik returns the desynchronized backend socket to its shared pool and reuses it for other clients. An unauthenticated attacker can use this behavior to make a different client read the attacker's smuggled response, which can include authenticated or private content from another request. The ForwardAuth middleware with forwardBody true and preserveRequestMethod true can re-issue a CONNECT with the buffered body attached, exposing the auth-client pool to the same desynchronization. This issue is fixed in 2.11.53, 3.6.24, and 3.7.9.
Weakness: CWE-444
Which versions are affected by CVE-2026-71324?
11 open source packages ship an affected version, including github.com/traefik/traefik/v3, github.com/traefik/traefik and github.com/traefik/traefik/v2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/traefik/traefik/v3 Go | All versions | 3.6.24, 3.7.9 |
github.com/traefik/traefik/v3 Go | All versions | 3.6.24 |
github.com/traefik/traefik/v3 Go | All versions | 3.6.24 |
github.com/traefik/traefik/v3 Go | From 3.7.0 | 3.7.9 |
github.com/traefik/traefik/v3 Go | From 3.7.0 | 3.7.9 |
github.com/traefik/traefik Go | All versions | None |
5 more packages
github.com/traefik/traefik Go | All versions to 1.7.34 | None |
github.com/traefik/traefik Go | All versions to 1.7.34 | None |
github.com/traefik/traefik/v2 Go | All versions | 2.11.53 |
github.com/traefik/traefik/v2 Go | All versions | 2.11.53 |
github.com/traefik/traefik/v2 Go | All versions | 2.11.53 |
Products include Traefik Traefik.
How do I fix CVE-2026-71324?
Upgrade github.com/traefik/traefik/v3 to a fixed version for your release line: 3.6.24 or 3.7.9.
Is CVE-2026-71324 being exploited?
There is no known exploitation of CVE-2026-71324 in the wild and no public exploit code.
Other vulnerabilities in Traefik Traefik
- CVE-2024-45410 HTTP client can remove the X-Forwarded headers in Traefik
- CVE-2026-88877 Traefik v3.7.0 Authentication Bypass via from-to-www-redirect
- CVE-2026-85595 Traefik before v2.11.55 and v3.0.0 through v3.7.10 Authentication Bypass via digestAuth
- CVE-2026-88007 Traefik HTTP/3 Backend NTLM Connection Reuse
- CVE-2026-88009 Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing path-scoped routing, middleware guards and access logging
Sources
Also known as GHSA-3ccp-42pg-hgv6, GO-2026-6201, MINI-mf3v-fcvh-jhrx, MINI-rgh9-m5r7-xq4g, MINI-w45r-wpqg-9f4j.