CVE-2026-88008
Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization
- State
- Published
- Severity
- 7.0 High
- Published
- Sep 10, 2026
- Updated
- Sep 10, 2026
- Reserved
- Sep 9, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 7.0 High | 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 | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
traefiktraefik |
|
References
- https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326
- https://github.com/traefik/traefik/pull/13797
- https://github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3
- https://github.com/traefik/traefik/releases/tag/v2.11.57
- https://github.com/traefik/traefik/releases/tag/v3.7.13
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