CVE-2026-57580 authentik: Account Takeover via SAML NameID Comment Truncation

authentik is an open-source identity provider. Prior to 2026.2.6 and 2026.5.5, an inbound SAML Source configured with the non-default USERNAMELINK or EMAILLINK user-matching mode interprets an XML comment in a NameID differently from the identity provider's signed assertion. An attacker with an...