Papra is a minimalistic document management and archiving platform. Prior to 26.4.0, transactional email templates in Papra interpolate user.name directly into HTML without escaping or sanitization. An attacker who registers with a display name containing HTML tags will have those tags injected into the verification and password reset email bodies. Since emails are sent from the legitimate domain (e.g: auth@mail.papra.app), this enables convincing phishing attacks that appear to originate from official Papra notifications. This vulnerability is fixed in 26.4.0.