eMudhra certificate alert: How to update Windows, macOS and Linux devices for better security

The eMudhra certificate incident has raised questions about how computers decide which websites and online services to trust. India's cybersecurity agency CERT-In says weak cryptographic key generation made the private keys of eight intermediate certificate authorities recoverable.

Google and Mozilla have taken steps to block the affected website certificates. However, keeping your computer updated remains an important security measure because browsers, operating systems and individual applications may manage certificate trust differently.

Installing operating system updates can deliver security fixes and updated certificate information. However, it does not guarantee that every application or server has stopped trusting the affected certificates. Some applications, including certain PHP applications, rely on separate certificate bundles that may require individual updates. CERT-In’s advisory provides further details about the incident and recommended precautions.

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How to update Windows

Microsoft recommends installing available Windows updates to keep your computer secure.

1. Open Settings on your Windows PC.
2. Select Windows Update. On Windows 10, go to Settings > Update & Security > Windows Update.
3. Click Check for updates.
4. If updates are available, select Download and install.
5. Restart your computer if prompted.

Follow Microsoft’s official Windows update guide for further instructions.

Note that standard support for Windows 10 ended on October 14, 2025. If you still use Windows 10, check whether your device is enrolled in an applicable Extended Security Updates programme or consider upgrading to a supported operating system. Microsoft’s support page explains the available options.

How to update macOS

Apple recommends keeping your Mac updated with the latest software version available for your device.

1. Click the Apple menu and open System Settings.
2. Select General, followed by Software Update.
3. Wait for your Mac to check for available updates.
4. If an update is available, select Update Now or the relevant update option and follow the instructions.

Back up important files before a major operating system upgrade. See Apple’s official macOS update guide.

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How to update Linux

The steps depend on your Linux distribution.

On Ubuntu, open the Terminal and run: sudo apt update

Then run: sudo apt upgrade

The first command refreshes the list of available packages from configured repositories, while the second installs available package updates.

On Red Hat Enterprise Linux systems that use DNF, administrators can run: sudo dnf upgrade

Install updates from your distribution’s trusted repositories. If you manage a server, check your distribution’s security advisories and confirm whether an updated certificate package is available. These commands update packages, and they do not, by themselves, guarantee that a specific eMudhra-related certificate issue has been resolved. Follow your organisation’s change-management procedures before updating production systems.

Ubuntu provides an official guide to package updates.

Does updating your computer fix the eMudhra risk?

Not necessarily. Browser vendors can block affected certificates through browser-specific mechanisms, while other applications may rely on operating system or application-specific certificate trust stores.

This distinction matters for some server-side applications, including PHP applications that use separate certificate bundles. Updating your personal computer does not automatically fix an affected website’s backend.

Website owners and administrators should check their software vendors’ guidance, update affected certificate bundles where required, and verify that their systems no longer trust the affected certificate chains.