Calibre-web 0.6.21 - Stored XSS

# Exploit Title: Stored XSS in Calibre-web
# Date: 07/05/2024
# Exploit Authors: Pentest-Tools.com (Catalin Iovita & Alexandru Postolache)
# Vendor Homepage: (https://github.com/janeczku/calibre-web/)
# Version: 0.6.21 - Romesa
# Tested on: Linux 5.15.0-107, Python 3.10.12, lxml	4.9.4
# CVE: CVE-2024-39123

## Vulnerability Description
Calibre-web 0.6.21 is vulnerable to a Stored Cross-Site Scripting (XSS) vulnerability. This vulnerability allows an attacker to inject malicious scripts that get stored on the server and executed in the context of another user's session.

## Steps to Reproduce
1. Log in to the application.
2. Upload a new book.
3. Access the Books List functionality from the `/table?data=list&sort_param=stored` endpoint.
4. In the `Comments` field, input the following payload:

    <a href=javas%1Bcript:alert()>Hello there!</a>

4. Save the changes.
5. Upon clicking the description on the book that was created, in the Book Details, the payload was successfully injected in the Description field. By clicking on the message, an alert box will appear, indicating the execution of the injected script.