The company that requested the penetration test is responsible for providing the correct and accurate network scope for the test. The network scope defines the boundaries and limitations of the test, such as which IP addresses, domains, systems, or networks are in scope or out of scope. If the company provided an incorrect network scope that included an IP address that belongs to a third party, then it is responsible for this mistake.
The penetration testing company, the target host's owner, the penetration tester, and the subcontractor supporting the test are not responsible for this mistake, as they relied on the network scope provided by the company that requested the penetration test.

Insecure Direct Object References (IDOR) occur when an application provides direct access to objects based on user-supplied input. In the provided URLs, the userid parameter is directly referenced, which can allow attackers to manipulate these references to access unauthorized data. This vulnerability can lead to unauthorized access to other users' profiles by simply changing the userid parameter value. The other vulnerabilities listed (Improper error handling, Race condition, Weak or default configurations) do not directly relate to the issue demonstrated by the URLs.

Credential harvesting is a type of attack that aims to collect usernames and passwords from unsuspecting users by tricking them into entering their credentials on a fake or spoofed website. Credential harvesting can be done by using phishing emails that lure users to click on malicious links or attachments that redirect them to the fake website. The fake website may look identical or similar to the legitimate one, but it will capture and store the user's credentials for later use by the attacker. In this case, the penetration tester set up a fake cloud mail login page and sent phishing emails to all company employees to harvest their credentials.

The output of the fuzzing tool shows that the admin, test, and db directories have the same size, words, and lines as the login page, which indicates that they are redirecting to the login page. This means that the tester cannot access these directories without valid credentials. The server-status page returns a 403 Forbidden status code, which means that the tester does not have permission to access it. The robots.txt file returns a 404 Not Found status code, which means that the file does not exist on the server. References:
*The Official CompTIA PenTest+ Study Guide (Exam PT0-002), Chapter 2: Conducting Passive Reconnaissance, page 77-78.
*101 Labs - CompTIA PenTest+: Hands-on Labs for the PT0-002 Exam, Lab 2.3: Fuzzing Web Applications, page 69-70.