{"id":"CVE-2026-47203","summary":"Authelia Missing Username Canonicalization in Basic Auth (LDAP)","details":"Authelia is an open-source authentication and authorization server providing two-factor authentication and single sign-on (SSO) for applications via a web portal. In versions 4.38.0 through 4.39.19, when a user authenticates via Basic Auth (i.e via the `Authorization` header with the `Basic` scheme) on the authz verification endpoint, Authelia takes the username directly from the `Authorization` header and passes it as is to the regulation system for ban checking and attempt recording. LDAP treats usernames case insensitively : `john`, `John`, and `JOHN` all bind as the same user. But the regulation SQL queries treat the lookup of these values in certain scenarios as case sensitive. This allows each variation of a usernames case to have its own ban bucket. Upgrade to 4.39.20 to receive a patch. As a workaround, explicitly disable the basic auth mechanism.","aliases":["GHSA-hjj4-hfjm-fmrj","GO-2026-5430"],"modified":"2026-07-08T08:13:39.689117093Z","published":"2026-06-19T20:19:47.903Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47203.json","cwe_ids":["CWE-178","CWE-307"],"cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47203.json"},{"type":"ADVISORY","url":"https://github.com/authelia/authelia/security/advisories/GHSA-hjj4-hfjm-fmrj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47203"},{"type":"FIX","url":"https://github.com/authelia/authelia/commit/b8985b57b70acdff8f204ed426ff619e763461ad"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/authelia/authelia","events":[{"introduced":"a53395fd7e4f40f0ac26e29a0b722c52c3015a06"},{"fixed":"1b524f7f4bbf7b5637f4c6b98f4f66fd4b4aed91"}],"database_specific":{"extracted_events":[{"introduced":"4.38.0"},{"fixed":"4.39.20"}],"source":"AFFECTED_FIELD"}}],"versions":["v4.39.19","v4.39.18","v4.39.17","v4.39.16","v4.39.15","v4.39.14","v4.39.13","v4.39.12","v4.39.11","v4.39.10","v4.39.9","v4.39.8","v4.39.7","v4.39.6","v4.39.5","v4.39.4","v4.39.3","v4.39.2","v4.39.1","v4.39.0","v4.38.19","v4.38.18","v4.38.17","v4.38.16","v4.38.15","v4.38.14","v4.38.13","v4.38.12","v4.38.11","v4.38.10","v4.38.9","v4.38.8","v4.38.7","v4.38.6","v4.38.5","v4.38.4","v4.38.3","v4.38.2","v4.38.1","v4.38.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-47203.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P"}]}