Passbolt API before 5, if the server is misconfigured (with an incorrect installation process and disregarding of Health Check results), can send email messages with a domain name taken from an attacker-controlled HTTP Host header.
Passbolt API before 4.6.2 allows HTML injection in a URL parameter, resulting in custom content being displayed when a user visits the crafted URL. Although the injected content is not executed as JavaScript due to Content Security Policy (CSP) restrictions, it may still impact the appearance and user interaction of the page.