{"id":"CVE-2026-88011","revision":"dc95b4fdb9a243a3ac506839aa9cd192","records":[{"revision":"dc95b4fdb9a243a3ac506839aa9cd192","observedAt":"2026-10-25T16:19:22.228+00:00","statement":{"source":"nvd","id":"CVE-2026-88011","aliases":[],"title":"Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy bec…","description":"Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User while normalization-prone CGI, WSGI, PHP, and NGINX backends collapse both names. A backend can consequently consume the client value instead of the identity Traefik asserted, allowing identity spoofing for any header managed by Traefik. The aliasHeadersStrategy protection is disabled by default and must be configured as delete or reject. The mitigation is available in 2.11.56 and 3.7.12.","state":0,"publishedAt":"2026-09-10T16:18:07.933+00:00","modifiedAt":"2026-09-15T15:17:24.163+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","score":5.3,"severity":"MEDIUM"},{"system":"CVSS 3.1 · nvd@nist.gov · Primary","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N","score":8.1,"severity":"HIGH"}],"references":["https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbecf8","https://github.com/traefik/traefik/pull/13720","https://github.com/traefik/traefik/releases/tag/v2.11.56","https://github.com/traefik/traefik/releases/tag/v3.7.12","https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8c"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-88011","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-290"],"productCriteria":["cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2026-09-10T16:18:07.933","lastModified":"2026-09-15T15:17:24.163"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-88011","identifiers":["CVE-2026-88011"]},"retained":false,"historicalAffected":[]}],"coverage":[]}