CVE-2026-47203: Authelia is an open-source authentication and authorization server providing two-factor authentication and single sign-on (SSO) for applications via a web…

PriorityP420low2.9CVSS 4.0

AVNACHATPPRNUINVCLVINVANSCNSINSANEPCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX

EPSS

0.31%

22.5th percentile

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.

Affected

2 ranges

Vendor	Product	Version range	Fixed in
authelia	authelia	—	—
github.com	authelia_authelia_v4	>= 4.38.0 < 4.39.20	4.39.20

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