Why unpatched software is a problem

Modern software constantly receives updates (patches) to fix bugs and security holes. When those patches are not applied, the software remains vulnerable. Attackers actively look for unpatched systems because known vulnerabilities are easy entry points. Unpatched software can lead to data breaches, ransomware, service outages, and regulatory penalties.

Common causes of patch delays include limited downtime windows, testing needs, resource constraints, and unsupported (legacy) systems. A proactive patch management process, including prioritizing urgent fixes, maintaining device inventory, and using automated updates, helps reduce risk.

What is unpatched software?

Boston University says, “Patches are software and operating system (OS) updates that address security vulnerabilities within a program or product. Software vendors may choose to release updates to fix performance bugs, as well as to provide enhanced security features.”

Unpatched software refers to any computer program, operating system, application, or device software that has known vulnerabilities for which a patch is available but has not been applied. The vendor has issued a fix for a flaw, but the system still runs the older, vulnerable version.

The CISA Joint Cybersecurity Advisory notes that running unpatched software “may allow an attacker to exploit publicly known vulnerabilities to gain access to sensitive information, launch a denial-of-service attack, or take control of a system.” An unpatched piece of software is simply not up-to-date with the latest security patches.

Why are patches released?

Boston University says employees should “install updates as soon as possible to protect your computer, phone, or other digital device against attackers who would take advantage of system vulnerabilities. Attackers may target vulnerabilities for months or even years after updates are available.”

Software patches (updates) are released by vendors to fix problems discovered in their products. These problems can include security vulnerabilities, software bugs, stability issues, or performance problems. The CISA goes on to note patches are “software and operating system (OS) updates that address security vulnerabilities within a program or product,” and may also fix performance bugs or add security features.

When a flaw or weakness is found (often assigned a CVE number), the vendor develops a patch so attackers cannot exploit that flaw. NIST notes that known, unpatched vulnerabilities are a root cause of many breaches and that good patching practices “can prevent many incidents.”

Why attackers target unpatched software

Attackers target unpatched software because it provides an easy, low-cost way into systems. When a vulnerability is publicly disclosed (and assigned a CVE number), details and often exploit code become available. An unpatched system still has that weakness open for anyone to use. As the NSA, CISA, FBI, and international partners warn in another 2022 joint advisory, malicious cyber actors “continued exploiting known software vulnerabilities to target unpatched systems and applications,” including vulnerabilities “known for more than five years.”

Neal Ziring, Technical Director for NSA’s Cybersecurity Directorate, put the risk plainly: “Organizations continue using unpatched software and systems, leaving easily discovered openings for cyber actors to target.” He added that “older vulnerabilities can provide low-cost and high impact means for these actors to access sensitive data.”

The pattern is a small part of a bigger healthcare security problem. Paubox’s 2026 Healthcare Email Security Report found that 41% of healthcare organizations assessed after email-related breaches were considered high risk, up from 31% in 2024, showing how attackers benefit when basic security controls remain weak or inconsistently enforced.

Attackers also scan the internet for systems missing common patches. Since patch updates close known vulnerabilities, failing to apply them leaves a predictable entry point. The advisory notes that several vulnerabilities remained among the top routinely exploited flaws across multiple years, showing that attackers keep returning to old weaknesses when organizations do not fix them. NIST also points out that “attackers regularly exploit unpatched software” and that delaying patches gives “attackers a larger window of opportunity.”

Why patch delays happen

Patching delays often happen for practical, operational reasons. Even when a patch is available, organizations sometimes postpone it because of concerns about downtime, testing, or compatibility. NIST notes that patching is resource-intensive and “can reduce system and service availability" and that many organizations “struggle to prioritize patches, test patches before deployment, and adhere to policies."

Specific factors include limited maintenance windows (e.g., you cannot reboot 24/7-critical systems easily), fear that a patch might break an application, and simply not having enough IT staff or tools to roll out updates quickly. Other causes are a lack of clear asset inventories (so IT may not even know all the vulnerable systems), dependency on third-party vendors for patches, and a backlog of updates. Patching can be complex, so it often gets delayed.

See also: HIPAA Compliant Email: The Definitive Guide (2026 Update)

FAQs

What is the difference between patch management and vulnerability management?

Patch management focuses on applying software updates that fix known problems. Vulnerability management is broader.

Should organizations install every patch immediately?

Not every patch can be installed blindly. NIST’s guidance recognizes the tradeoff between fast deployment and testing. Deploying patches quickly can reduce the attacker’s window of opportunity, but testing helps reduce the risk of operational disruption.

Why do attackers keep using old vulnerabilities?

Attackers keep using old vulnerabilities because many organizations still do not patch them. Older flaws are attractive because exploit methods are often well understood, scanning is easier, and attackers can find exposed systems at scale.