CVE-2021-40658: Textpattern 4.8.7 is affected by HTML injection in the Body parameter.

#Exploit Title: Textpattern CMS v4.8.7 “Content>Write>Body” — HTMLi
# Exploit Author: Tanmay Bhattacharjee
# Vendor Homepage: https://www.textpattern.co
# Software Link: https://textpattern.com/start
# Version: 4.8.7
# Tested on: Ubuntu

Vulnerable Parameters: Body.

Attack Vector:
This vulnerability can results attacker to inject the HTML src & href attributes payload into the body parameter.

Steps-To-Reproduce:
1. Login into Textpattern CMS admin panel.
2. Now go to the Content > Write > Body.
3. Now paste the below payload in the URL field.
<script src=”data:,alert(document.cookie)”></script>
4. Now click on publish button and click on view button. Boom Boom Boom
5. The HTML payload triggered successfully and give us cookie info with user information.

No bruteforcing, happy with manual testing.

Have a nice day.

Thanks,

Tanmay