{"id":"CVE-2026-71326","summary":"Traefik: BasicAuth singleflight key collision allows authenticated identity spoofing","details":"Traefik is an open source HTTP reverse proxy and load balancer. From 3.6.11 until 3.6.25 and 3.7.10, Traefik's BasicAuth middleware in pkg/middlewares/auth/basic_auth.go deduplicates concurrent password checks with a singleflight key built from the delimiter-free concatenation of password and secret, allowing an attacker who has a valid credential and the stored hash to authenticate as an unconfigured username when headerField trusts the forwarded identity. This issue is fixed in 3.6.25 and 3.7.10.","aliases":["GHSA-6765-c87h-8mrf","GO-2026-6204"],"modified":"2026-08-18T15:10:47.240700768Z","published":"2026-08-06T16:34:23.931Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71326.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-287"]},"references":[{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v3.6.25"},{"type":"WEB","url":"https://github.com/traefik/traefik/releases/tag/v3.7.10"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/71xxx/CVE-2026-71326.json"},{"type":"ADVISORY","url":"https://github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8mrf"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-71326"},{"type":"FIX","url":"https://github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2d9e08b7e350"},{"type":"FIX","url":"https://github.com/traefik/traefik/pull/13572"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/traefik/traefik","events":[{"introduced":"33219a0af86c41a8db81d37c444f65172bfb3e35"},{"introduced":"04aa6bb4f9776f2ba87e5cd181d250e3610e6419"},{"fixed":"4b18b24b0b002dcc80e0640c6088a87d813de29a"},{"fixed":"2a2349356c01b1b1f7ecddb0c17b30c97f5241e7"},{"fixed":"b5ace8eb5d6779980567f5e75efd2d9e08b7e350"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"3.6.11"},{"fixed":"3.6.25"},{"introduced":"3.7.0"},{"fixed":"3.7.10"}]}}],"versions":["v3.7.9","v3.6.24","v3.7.8","v3.6.23","v3.7.7","v3.7.6","v3.6.22","v3.6.21","v3.7.5","v3.6.20","v3.7.4","v3.7.3","v3.6.19","v3.7.2","v3.6.18","v3.6.17","v3.7.1","v3.6.16","v3.7.0","v3.6.15","v3.6.14","v3.6.13","v3.6.12","v3.6.11"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-71326.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N"}]}