Managing vulnerabilities
The majority of cyber security incidents are the result of attackers exploiting publicly disclosed vulnerabilities to gain access to systems and networks. Attackers will, often indiscriminately, seek to exploit vulnerabilities as soon as they have been disclosed. So, it is important (and essential for any systems that are exploitable from the internet) to install security updates as soon as possible to protect your organisation.
Some vulnerabilities may be harder to fix, and a good vulnerability management process will help you understand which ones are most serious and need addressing first.