OS security: what to check on your device

The name Windows, macOS, Linux, Android, or iOS alone cannot establish the risk to a particular device. Check its version and support period, installed updates, apps, and permissions. Built-in protection does not guarantee the absence of vulnerabilities or malware.

Start with the system version and available updates. Then check software sources and permissions. The platform conditions and checking instructions follow below.

What Actually Drives Risk for an OS

For your device, check:

• Support for the installed release: whether it receives fixes and under what conditions.
• Updates: what is installed, what needs a restart, and whether installation errors remain.
• Apps and packages: where they came from and who provides fixes for them.
• Permissions: which apps can access data, hardware, and administrator functions.

A platform's user count, the number of published vulnerabilities, and the likelihood of an attack on your device are different measures. Do not use one as a ready-made estimate of the others.

Windows: version support and built-in protection

For Windows, check the edition, version, and applicable support period. Regular support for Windows 10 ended on October 14, 2025. Specific LTSC editions and the Extended Security Updates (ESU) program have their own conditions. Having Windows 10 or an installed antivirus does not confirm that the OS receives security fixes.

The Windows Security app shows protection status. Microsoft describes its antivirus protection and device scanning options. Added exclusions can leave selected files unchecked by Microsoft Defender.

Do not disable protection or add an exclusion just to run an unknown program. For a work device, check restrictions and updates with your administrator. Further measures are covered in the home PC security guide.

macOS: Gatekeeper, XProtect, and updates

Apple describes several macOS protection tools: Gatekeeper, notarization, and XProtect. They check program execution and known malware; XProtect is also designed to remove malware. These are protection features, not proof that every Mac is free of malicious software.

An app's notarization can be revoked if Apple later discovers malware. Earlier permission to run should therefore not be treated as a permanent safety guarantee.

Check updates available for your Mac model. Do not bypass a system warning just because an app promises optimization. Further risks of apps and official stores are covered separately.

Linux: distribution, packages, and support period

For Linux, check the particular distribution, its release, and installed packages. For example, Canonical separately describes the duration and scope of standard Ubuntu security maintenance and extended programs. A release's support period does not mean all installed third-party packages receive the same maintenance.

On March 29, 2024, Red Hat reported malicious code in XZ libraries, versions 5.6.0 and 5.6.1. Its notice distinguished Fedora Rawhide, Fedora 40 beta, and RHEL; the company stated that no RHEL versions were affected. This concerned particular packages and builds, not an infection of every Linux system.

Check your distribution's notice and whether its conditions match the installed version. Do not apply an old package downgrade procedure to today's system without checking. Grant administrator privileges only for a task you understand.

Mobile Operating Systems: Android and iOS

For Android, check the device model, system version, and security update date. Google states that the update schedule depends on the device, manufacturer, and carrier. The Android version number alone does not show which fixes are installed.

On devices with Google Play Protect, it checks apps at installation and periodically scans the device. It can also warn about potentially harmful apps from other sources. A scan is not a guarantee that every app is safe.

For iPhone, check the installed iOS version and updates offered to a compatible device. Do not apply one model's conditions to all Android or Apple devices. There is a separate comparison of Android and iOS.

Further measures are covered in the smartphone security guide.

What to check beyond the OS name

Check system updates, app updates, and permissions separately. An OS fix does not confirm that all programs are updated. Before granting access to the camera, microphone, or contacts, identify the function that needs it. See the guide to checking apps' microphone access.

Software sources also need checking. Find the developer's official website, store, or repository and check the publisher. An app being in a store does not establish that it has no bugs or unwanted data processing.

Distinguish connection protection from device security. With correctly configured HTTPS, connection content is protected from ordinary reading by an intermediary. A VPN protects traffic routed through it between the device and VPN server, but does not install OS fixes or override app permissions. Public Wi-Fi risks are covered separately.

How to Reduce Risk on Any OS

Before changing settings:

1. Record the device model, OS edition, and version.
2. Check the support period and conditions for receiving fixes with the manufacturer or distribution.
3. Save the files you need and check that your backup is available before updating.
4. Check the sources of installed programs and their available updates.
5. Review the permissions of the app you need. Remove unnecessary access, then check its function.
6. Use unique passwords and two-factor authentication for important accounts. See the strong password guide.
7. For a work device, agree changes with your administrator. Do not treat a separate profile as a guarantee that all data is isolated.

Check saved settings and update installation results. These steps' comparative advantage over changing OS is not measured here.

How to check Windows 11 updates

1. Open Start → Settings → Windows Update.
2. Run a check for available updates.
3. If updates are offered, read the conditions and follow the installation instructions. Save open files before restarting.
4. After installation and any required restart, reopen the update section. Record any remaining error or installation status.

Checking updates is not a malware scan. For Windows 10, separately check the edition, support period, and ESU enrollment; this procedure does not confirm that it receives fixes.

How to check macOS updates

1. Open the Apple menu → System Settings.
2. Select General → Software Update.
3. Check the offered update. Save a backup before installing and follow Apple's instructions.
4. After installation, reopen Software Update and check the status.

This section shows software compatible with the Mac model. No update being offered does not establish that there are no vulnerabilities. If the path differs in an older version, use Apple's help for that version.

How to check the Android version and updates

1. Open Settings, then About phone or About tablet, then Android version.
2. Record the Android version, security update date, and build number.
3. Return to Settings and open System → Software updates, if your device has this path.
4. Check the status and follow the instructions for the available update. Check the version information again after completion.

The path and update schedule depend on the device and manufacturer. If the entries differ, use the help for your model. One update date is not an assessment of the phone's overall security.

How to check iPhone updates

1. Before installation, back up your data following Apple's instructions.
2. Open Settings → General → Software Update.
3. Check the installed iOS version and update availability.
4. If you decide to install an offered update, follow the onscreen instructions. Check the version again after completion.

Update availability depends on device compatibility. A working phone and no offered update do not establish the absence of known or unknown vulnerabilities.

How to check an app's permissions on Android

1. Open Settings → Apps.
2. Select the app. If it is not visible, open See all apps.
3. Open Permissions.
4. Select a permission and check the available setting. If access is unnecessary, select Don't allow.
5. Reopen the app and check the function you need. Review access for that function if necessary.

The path and available settings can differ by device and Android version. Denying a permission does not delete previously transmitted records or replace an app update.

So Which OS Is “Most Vulnerable”?

Without matching conditions and comparable data, one system cannot be called the most vulnerable for all devices and tasks. The OS name does not replace checking the edition, support, packages, and permissions.

If support has ended, check the available move to a supported release or applicable extended update conditions. If an update failed, save the exact error and use the manufacturer's help. If you restricted a permission, check its saved state and the app's operation again.

The absence of a warning or an available update does not prove that the device is fully protected. For a work device, give the results to your administrator without publishing passwords or access keys.