CVE-2026-88008 PUBLISHED

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

Assigner: GitHub_M
Reserved: 09.09.2026 Published: 10.09.2026 Updated: 10.09.2026

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.

Metrics

CVSS 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
CVSS Score: 7

Product Status

Vendor traefik
Product traefik
Versions
  • Version >= 2.11.26, < 2.11.57 is affected
  • Version >= 3.4.2, < 3.7.13 is affected

References

Problem Types

  • CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') CWE
  • CWE-863: Incorrect Authorization CWE