{"id":"CVE-2026-88008","summary":"Traefik: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') and Incorrect Authorization","details":"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.","aliases":["GHSA-w4v4-9rw7-5326"],"modified":"2026-09-12T03:47:21.056001564Z","published":"2026-09-10T14:57:06.162Z","database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-444","CWE-863"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88008.json"},"references":[{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v2.11.57"},{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v3.7.13"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/88xxx/CVE-2026-88008.json"},{"type":"ADVISORY","url":"https://github.com/traefik/traefik/security/advisories/GHSA-w4v4-9rw7-5326"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-88008"},{"type":"FIX","url":"https://github.com/traefik/traefik/commit/a277e94664ffc1ce9543df552d3bbf48d4d3b8b3"},{"type":"FIX","url":"https://github.com/traefik/traefik/pull/13797"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/traefik/traefik","events":[{"introduced":"8ae0379171cd04b60d7a1cb7da124ef56e8fc9f1"},{"introduced":"a51918066548a919cf8d46c8c5193cd5ab52a999"},{"fixed":"839eb7f48a16849f22762b7e3bdfc58253146cd7"},{"fixed":"fc92cc118a0557a029c7019d5ee06665127b0f13"},{"fixed":"a277e94664ffc1ce9543df552d3bbf48d4d3b8b3"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"2.11.26"},{"fixed":"2.11.57"},{"introduced":"3.4.2"},{"fixed":"3.7.13"}]}}],"versions":["v2.11.56","v2.11.55","v2.11.54","v2.11.53","v2.11.52","v2.11.51","v2.11.50","v2.11.49","v2.11.48","v2.11.47","v2.11.46","v2.11.45","v2.11.44","v2.11.43","v2.11.42","v2.11.41","v2.11.40","v2.11.39","v2.11.38","v2.11.37","v2.11.36","v2.11.35","v2.11.34","v2.11.33","v2.11.32","v2.11.31","v2.11.30","v2.11.29","v2.11.28","v2.11.27","v2.11.26"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-88008.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}