CVE-2026-33525

/// Technical 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 version 4.39.15, an attacker may potentially be able to inject javascript into the Authelia login page if several conditions are met simultaneously. Unless both the `script-src` and `connect-src` directives have been modified it's almost impossible for this to have a meaningful impact. However if both of these are and they are done so without consideration to their potential impact; there is a are situations where this vulnerability could be exploited. This is caused to the lack of neutralization of the `langauge` cookie value when rendering the HTML template. This vulnerability is likely difficult to discover though fingerprinting due to the way Authelia is designed but it should not be considered impossible. The additional requirement to identify the secondary application is however likely to be significantly harder to i

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References