Authentication Bypass in Authelia Open-Source Authentication Server
CVE-2026-47203

2.9LOW

Key Information:

Vendor

Authelia

Status
Authelia
Vendor
CVE Published:
19 June 2026

What is CVE-2026-47203?

The vulnerability in Authelia arises when users authenticate via Basic Auth on the authorization verification endpoint. Due to the handling of usernames, which are treated case insensitively by LDAP but can be case-sensitive in regulation SQL queries, multiple variations of the same username can create separate ban buckets. This allows for potential circumvention of security measures, leading to unauthorized access. Users are encouraged to upgrade to version 4.39.20, which includes necessary patches. A temporary workaround is to disable the Basic Auth mechanism.

Affected Version(s)

authelia >= 4.38.0, < 4.39.20

References

https://github.com/authelia/authelia/security/advisories/...
x_refsource_CONFIRM
https://github.com/authelia/authelia/commit/b8985b57b70ac...
x_refsource_MISC

CVSS V4

Score:
2.9
Severity:
LOW
Confidentiality:
Low
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
Physical
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.