CVE-2026-47203CWE-178CWE-307

Authelia Missing Username Canonicalization in Basic Auth (LDAP)

Low · published June 19, 2026

CVSS v4.0
2.9
EPSS
0%
Percentile
38.3
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
2.9 · LOW
Vector
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
EPSS
0.00453 · 38.3th percentile
Weaknesses
CWE-178 · Improper Handling of Case Sensitivity; CWE-307 · Improper Restriction of Excessive Authentication Attempts
Published
2026-06-19T20:19Z
EPSS history
Timeline
  • 19 JUN 20:19Z
    Authelia Missing Username Canonicalization in Basic Auth (LDAP)
    cvelistv5