Authelia Missing Username Canonicalization in Basic Auth (LDAP)

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Summary

CVECVE-2026-47203
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-19 21:16:57 UTC
Updated2026-06-19 21:16:57 UTC
DescriptionAuthelia 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.

Risk And Classification

Primary CVSS: v4.0 2.9 LOW from [email protected]

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Problem Types: CWE-178 | CWE-307 | CWE-178 CWE-178: Improper Handling of Case Sensitivity | CWE-307 CWE-307: Improper Restriction of Excessive Authentication Attempts

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.9LOWCVSS: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/C...
4.0CNADECLARED2.9LOWCVSS: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

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
High
Attack Requirements
Present
Privileges Required
None
User Interaction
None
Confidentiality
Low
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Authelia Authelia affected >= 4.38.0, < 4.39.20 Not specified

References

ReferenceSourceLinkTags
github.com/authelia/authelia/commit/b8985b57b70acdff8f204ed426ff619e7634... [email protected] github.com
github.com/authelia/authelia/security/advisories/GHSA-hjj4-hfjm-fmrj [email protected] github.com
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