WordPress Mimetic Books 0.2.13 Plugin - (Default Publisher ID field) XSS Vulnerability

# Exploit Title: WordPress Plugin Mimetic Books 0.2.13 - 'Default Publisher ID field' Stored Cross-Site Scripting (XSS)
# Exploit Author: Vikas Srivastava
# Vendor Homepage:
# Software Link: https://wordpress.org/plugins/mimetic-books/
# Version: 0.2.13
# Category: Web Application
# Tested on Mac

How to Reproduce this Vulnerability:

1. Install WordPress 5.7.2
2. Install and activate Mimetic Books
3. Navigate to Settings >> Mimetic Books API and enter the XSS payload into the Default Publisher ID input field.
4. Click Save Changes.
5. You will observe that the payload successfully got stored into the database and when you are triggering the same functionality at that time JavaScript payload is executing successfully and we are getting a pop-up.
6. Payload Used: "><script>alert(document.cookie)</script>