CVE-2026-40165
HighSummary
authentik is an open-source identity provider that was vulnerable to Authentication Bypass through SAML NameID XML Comment Injection in versions 2025.12.4 and prior, and 2026.2.0-rc1 through 2026.2.2. An attacker could manipulate the NameID value, potentially gaining access to other accounts.
Risk Assessment
Organizations using vulnerable versions of authentik may be exposed to unauthorized access to user accounts, leading to serious data security breaches.
Recommendation
It is recommended to upgrade to versions 2025.12.5 or 2026.2.3 to mitigate this vulnerability and secure the system against potential attacks.
Original NVD description (English source)
authentik is an open-source identity provider. Versions 2025.12.4 and prior, and versions 2026.2.0-rc1 through 2026.2.2 were vulnerable to Authentication Bypass through SAML NameID XML Comment Injection. Due to how authentik extracted the NameID value from a SAML assertion, it was possible for an attacker to trick authentik into only seeing a part of the NameID value, potentially allowing an attacker to gain access to other accounts. This issue could be exploited on an authentik instance with a SAML Source, where the attacker had an account on the SAML Source and the ability to modify their NameID value (commonly username or E-mail), and XML Signing was enabled. The attacker could modify the SAML assertion given to authentik by injecting a comment within the NameID value, which effectively truncated the NameID value to the snippet before the comment, and gave the attacker access to any user account. This issue has been fixed in versions 2025.12.5 and 2026.2.3.