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CVE-2026-47203GHSA-HJJ4-HFJM-FMRJGO-2026-5430

Authelia Missing Username Canonicalization in Basic Auth (LDAP)

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 4.39.20
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • authelia authelia

    From 4.38.0 · fixed in 4.39.20

  • github.com/authelia/authelia/v4Go

    From 4.38.0 · fixed in 4.39.20

  • github.com/authelia/autheliaGo

    All versions

References 2

GitHub · authelia/authelia