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Vulnerability · Published Sep 10, 2026 · Assigned by GitHub_M

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

High 7.0

In plain English

A high-severity incorrect authorization in traefik from traefik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.0High
Exploit odds (30 days)0.5%top 57.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack tooling1Public PoC

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/traefik/traefikno fix listedGO-2026-6468
Gogithub.com/traefik/traefik/v22.11.57GHSA-w4v4-9rw7-5326
Gogithub.com/traefik/traefik/v22.11.57GO-2026-6468
Gogithub.com/traefik/traefik/v33.7.13GHSA-w4v4-9rw7-5326
Gogithub.com/traefik/traefik/v33.7.13GO-2026-6468

Affected products (as reported)

VendorProductVersions
traefik traefik >= 2.11.26, < 2.11.57>= 3.4.2, < 3.7.13

Weakness: CWE-444, CWE-863 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N

References