CVE-2026-88008 Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization

What is CVE-2026-88008?

CVE-2026-88008 is a high-severity authentication bypass vulnerability in Traefik Traefik, published on 10 Sep 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. From 2.11.26 until 2.11.57 and 3.7.13, Traefik forwards a client-supplied Connection header requesting Upgrade, the Upgrade: h2c token, and HTTP2-Settings to a shared backend. If the backend accepts h2c and returns 101 Switching Protocols, Traefik enters a raw tunnel and no longer applies routers, BasicAuth, ForwardAuth, IPAllowList, RateLimit, access logging, metrics, or tracing to later HTTP/2 requests, allowing an unauthenticated request through an unprotected route to reach protected paths on the same backend. This issue is fixed in 2.11.57 and 3.7.13.

Weakness: CWE-863, CWE-444

Which versions are affected by CVE-2026-88008?

7 open source packages ship an affected version, including github.com/traefik/traefik/v2, github.com/traefik/traefik and github.com/traefik/traefik/v3. It affects 1 product.

Products include Traefik Traefik.

How do I fix CVE-2026-88008?

Upgrade github.com/traefik/traefik/v2 to 2.11.57 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-88008 being exploited?

There is no known exploitation of CVE-2026-88008 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in Traefik Traefik

• CVE-2024-45410 HTTP client can remove the X-Forwarded headers in Traefik Critical 9.8
• CVE-2026-88877 Traefik v3.7.0 Authentication Bypass via from-to-www-redirect Critical 9.3
• CVE-2026-85595 Traefik before v2.11.55 and v3.0.0 through v3.7.10 Authentication Bypass via digestAuth Critical 9.3
• CVE-2026-88007 Traefik HTTP/3 Backend NTLM Connection Reuse Critical 9.1
• CVE-2026-88009 Traefik: Rootless HTTP/1 request-target routes as "/" but is forwarded verbatim, bypassing path-scoped routing, middleware guards and access logging High 8.8

All Traefik Traefik vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ECHO-6de7-ef62-5b7d, GHSA-w4v4-9rw7-5326, GO-2026-6468, MINI-33wc-jmw5-h843, MINI-cjqg-pwmc-cjr3, MINI-mghp-9pwm-cmf9.