CVE-2026-40165— authentik: SAML NameID XML Comment Injection Enables Authentication Bypass via Identifier Truncation

authentik: SAML NameID XML Comment Injection Enables Authentication Bypass via Identifier Truncation

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.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N

认证机制不恰当

authentik 安全漏洞

authentik是authentik开源的一个开源身份提供应用程序。 authentik 2025.12.4及之前版本和2026.2.0-rc1至2026.2.2版本存在安全漏洞，该漏洞源于SAML NameID XML注释注入，可能导致攻击者绕过身份验证获取其他账户访问权限。

N/A

N/A