CVE-2026-47203
Authelia Missing Username Canonicalization in Basic Auth (LDAP)
Description
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.
INFO
Published Date :
June 19, 2026, 8:19 p.m.
Last Modified :
June 19, 2026, 8:19 p.m.
Remotely Exploit :
No
Source :
GitHub_M
Affected Products
The following products are affected by CVE-2026-47203
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Upgrade Authelia to version 4.39.20 or later.
- Disable basic authentication mechanism as a workaround.
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