From heimdalsecurity.com
Privilege escalation is a malicious tactic to misuse an app or OS issue or configuration problem to get unauthorized access to sensitive information by taking over a user’s account that would ordinarily be inaccessible to the current user.
By getting these permissions, a hostile actor may undertake a number of operations on the operating system or server, such as executing commands or aiding malware infection inside the network, which can cause business interruption, exposing of sensitive data, or system takeover. This is privilege abuse.