A telnet-related module is being imported. Using telnet is considered insecure. Consider the following points when using Telnet protocol:

• Telnet is a plain-text protocol, anyone watching your Telnet packets on the wire will see your username, password, and everything you do on the remote system.
• There are no authentication policies used in telnet causing huge security threat. Communication is carried out between the two desired hosts can be intercepted in the middle.

Use ssh as an alternative to telnet. It protects user identities, passwords, and data from network snooping attacks, and allows secure logins and file transfers. Use of telnet has been replaced by ssh in almost all cases.

Bad practice

import telnetlib # Sensitive, Import of telnetlib

url = "telnet://[email protected]"
connection = telnetlib.Telnet("somehost") # Sensitive, Using telnet protocol

Recommended

from paramiko import SSHClient

client = SSHClient()
url = "telnet://[email protected]"
client.connect(url, username='user', password='secret')

References:

• telnetlib module in Python
• Telnet security problems
• Paramiko module
• OWASP Top 10 2021 Category A06 - Vulnerable and Outdated Components
• SANS Top 25
• CWE-200