# CVE-2026-88008

## Summary

- **CVE ID:** CVE-2026-88008
- **Severity:** HIGH
- **CVSS Score:** 7 (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)
- **CWE:** CWE-444, CWE-863
- **Published:** Sep 10, 2026
- **Last Modified:** Sep 10, 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.

## Affected Products

- traefik — traefik (>= 2.11.26, < 2.11.57)
- traefik — traefik (>= 3.4.2, < 3.7.13)

## References

- [CNA](https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326)
- [CNA](https://github.com/traefik/traefik/pull/13797)
- [CNA](https://github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3)
- [CNA](https://github.com/traefik/traefik/releases/tag/v2.11.57)
- [CNA](https://github.com/traefik/traefik/releases/tag/v3.7.13)

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._