What Is Windows Security Update

A Windows security update is a patch from Microsoft that fixes security weaknesses in Windows. It changes affected software so attackers have fewer opportunities to exploit known flaws. Windows Update delivers these fixes, often within a cumulative update that also contains reliability improvements. Install applicable.

What Windows security updates fix

A vulnerability is a weakness in software that an attacker may be able to exploit. Depending on the flaw, an attack could allow someone to run malicious code, gain access to information or obtain permissions they should not have. Security updates repair the affected Windows components.

Installing a patch reduces exposure to the vulnerabilities it addresses. It does not guarantee protection against every attack, remove every existing infection or make unsafe downloads harmless. In particular, an update cannot fix a newly discovered vulnerability until a suitable fix is available.

Updates may also correct bugs that affect reliability, but a faster computer is not a guaranteed result. Their main security benefit is closing weaknesses rather than providing a general performance boost.

Windows Update and Windows Security do different jobs

Windows Update is the service and Settings area used to obtain Windows patches. Windows Security is the app where you can review protections such as antivirus and firewall settings. Their names are similar, but opening Windows Security or running an antivirus scan does not replace installing operating system updates.

Microsoft Defender Antivirus also receives security intelligence updates to help it recognise threats. These serve a different purpose from patches that repair Windows itself. Both need to stay current.

If you are trying to access security controls on a Lenovo laptop, our guide to finding Windows Security on a Lenovo ThinkPad covers that separate navigation question. Use Windows Update in Settings to check for operating system patches.

Which update types need attention

According to Microsoft's Windows update release guidance, monthly security updates normally arrive on the second Tuesday of each month, often called Patch Tuesday. Microsoft can also release an out-of-band update when an issue needs attention before the next scheduled release.

Monthly security updates are cumulative: they include earlier security fixes alongside new fixes and non-security changes. You generally do not need to find and install every previous monthly package individually.

How to install Windows security updates

Use the built-in Settings app rather than a download advertised by an unfamiliar website. Before starting, save your work, connect to the internet and plug a laptop into power. Keep a current backup of important files.

1. Open Start and select Settings.
2. In Windows 11, select Windows Update. In Windows 10, select Update & Security, then Windows Update.
3. Select Check for updates and allow Windows to identify applicable packages.
4. If prompted, select Download & install or the installation option shown. Wait for the process to finish.
5. Restart when requested. After signing in again, return to Windows Update and check for remaining updates or a pending restart.

These paths follow Microsoft's instructions for installing Windows updates. If you are navigating older settings, our guide to System and Security in Windows 10 explains related settings locations.

Manage restarts without leaving updates unfinished

Windows normally downloads and installs updates automatically, subject to device settings and organisational policies. Check that updates have not been left paused. Use active hours or schedule a restart when offered to reduce interruptions, then let the restart complete.

To confirm installation, open Update history from Windows Update. Look for the relevant update and its installation status. A downloaded package or a restart notification alone is not confirmation that installation has finished. On a work or school device, follow your IT team's update schedule and report persistent warnings.

Your Windows version must still be supported

An update check can only offer patches available for your edition, version and support arrangement. An old installation does not become secure simply because it reports that no updates are available.

Standard support for Windows 10 ended on 14 October 2025. Extended Security Updates and editions with separate lifecycles need their own eligibility and coverage checks. Microsoft's Windows 10 end-of-support guidance explains the available routes. If your installation is outside security support, plan a move to a supported system.

What to do when an update fails

Record the error code and update name before troubleshooting. A KB number identifies the Microsoft Knowledge Base article associated with an update and helps you find relevant instructions.

1. Check your internet connection and any message about insufficient storage. Free space using Windows storage settings if needed.
2. Save your work, restart the computer and try Windows Update again.
3. Run the automated Windows Update troubleshooter in the Get Help app, following Microsoft's troubleshooter guidance.
4. If installation still fails, give Microsoft Support or your IT team the error code, KB number and Windows version.

If a problem starts after an update, check Microsoft's notes for that update before removing it. Uninstalling a security patch can reopen the vulnerability it fixed, and some updates cannot be removed. Seek a documented workaround or support advice rather than repeatedly uninstalling patches.

Keep other protections working alongside updates

Keep antivirus protection and the firewall enabled, update your browser and applications, and maintain backups you can restore. Be cautious with unexpected attachments, sign-in requests and downloads. Operating system patches cover only one part of these everyday risks.

For help reviewing those settings, explore our Windows security guides.

Open Windows Update now, check for available security updates and schedule any required restart for a time when you can let it finish.