{"schemaVersion":3,"id":"CVE-2026-88008","aliases":["CGA-3cwp-4q99-5mgj","CGA-fjjg-v62q-23m8","CGA-r872-3x2j-x67p","CGA-vxgm-wfpc-hw85","GHSA-w4v4-9rw7-5326","GO-2026-6468","CGA-3g3c-vc25-7j4r","CGA-67fw-mpf9-pmww"],"status":"published","duplicateOf":null,"title":null,"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.","dates":{"published":"2026-09-10T14:57:06.162Z","modified":"2026-09-10T16:56:53.731Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":9.1,"severity":"critical","version":"3.1","versionLabel":"v3.1","source":"NVD","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N","computed":false,"selection":"backend-summary"},"metrics":[{"version":"4.0","versionLabel":"v4.0","source":"CVE.org","score":7,"severity":"high","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","exploitability":null,"impact":null,"computed":false},{"version":"4.0","versionLabel":"v4.0","source":"OSV · Wolfi","score":7,"severity":"high","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","exploitability":null,"impact":null,"computed":true},{"version":"4.0","versionLabel":"v4.0","source":"OSV · 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