The Qubes OS project has published Qubes OS 4.3.1, the new stable release of its security-focused operating system. It landed on June 11, 2026, as a maintenance update that gathers into a single ISO image all the security and bug fixes piled up since version 4.3.0, released in December 2025.
What is Qubes OS
Qubes OS is a reasonably secure operating system built around the principle of “security by compartmentalization.” Rather than running every application in the same environment, it splits the system into isolated virtual machines called qubes, managed through the Xen hypervisor. If one qube gets compromised, the rest of the system stays protected. It targets journalists, researchers, system administrators and anyone who needs a high level of security and privacy on their desktop machine.
What’s new in Qubes OS 4.3.1
This is a maintenance release within the 4.3 series, so the changes lean toward stability and security rather than big new features:
- Consolidated security updates, bundling the patches published through the Qubes Security Bulletins (QSB) since the previous stable release.
- Bug fixes accumulated between December 21, 2025 and May 28, 2026.
- Fedora template upgraded to Fedora 43, since Fedora 42 reached its end of life.
- A fresh ISO image ready for clean installations with all security patches up to date.
- Lets you install from scratch, upgrade from Qubes 4.2, or keep an existing 4.3 system current with a simple update.
It helps to recall what the 4.3 series brought: dom0 on Fedora 41, the Xen 4.19 hypervisor, default templates based on Fedora, Debian 13 and Whonix 18, plus new features like preloaded disposables, the new Devices API, and the return of the Qubes Windows Tools.
The timing matters too. The Qubes 4.2 series reached end of life on June 21, 2026, so if you are still running it, move to the 4.3 series as soon as you can to keep receiving security updates.
You can find all the details, requirements and download guides on the Qubes OS page at LinuxGratis.