CVE-2021-24159
Due to the lack of sanitization and lack of nonce protection on the custom CSS feature, an attacker could craft a request to inject malicious JavaScript on a site using the Contact Form 7 Style WordPress plugin through 3.1.9. If an attacker successfully tricked a site’s administrator into clicking a link or attachment, then the request could be sent and the CSS settings would be successfully updated to include malicious JavaScript.
Source: CVE-2021-24159