critical9.1
CVE-2026-88008
Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization
Impact
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
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| go | github.com/traefik/traefik/v3 | >= 3.4.2, < 3.7.13 | 3.7.13 |
| go | github.com/traefik/traefik/v2 | >= 2.11.26, < 2.11.57 | 2.11.57 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Traefik | Traefik | from 2.11.26 before 2.11.57 from 3.4.2 before 3.7.13 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-w4v4-9rw7-5326
- https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326
- https://nvd.nist.gov/vuln/detail/CVE-2026-88008
- 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