CVE-2026-88008
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.
Not on KEV
Not in CISA's Known Exploited Vulnerabilities catalogue as of the last daily pull. Absence is not proof of safety.
0%
Chance of exploitation in the next 30 days, 28th percentile of all CVEs. A forecast; KEV outranks it.
9.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
—
No exposure census on this CVE's dispatches.
- nvd.nist.gov ↗
- first.org · EPSS ↗
- github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3 ↗
- github.com/traefik/traefik/pull/13797 ↗
- github.com/traefik/traefik/releases/tag/v2.11.57 ↗
- github.com/traefik/traefik/releases/tag/v3.7.13 ↗
- github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326 ↗
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