Microsoft Launches Azure Linux 4.0, Its First Public Cloud-Only Linux Distribution

On June 2 2026 Microsoft made Azure Linux 4.0 publicly available as a free, open-source distro built on Fedora 43. The preview runs on Azure VMs, VM Scale Sets and AKS nodes, with a WSL version slated for later release.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or FedoraHow-To Geek

Microsoft launched the internal CBL-Mariner project in 2019 to supply a lightweight OS for Azure. By 2022 it powered LinkedIn, Databricks and Azure SQL. The project was renamed Azure Linux in March 2024, and version 4.0 now uses a Fedora 43 overlay.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

Former CEO Steve Ballmer once called Linux “a cancer that attaches itself in an intellectual property sense to everything it touches.” Microsoft now runs Azure Linux to own the cloud stack, reduce third-party OS costs and capture revenue like Amazon Linux and Google COS.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

Azure Linux 4.0 ships as a read-only 300 MB image with Linux 6.18 LTS, dnf5, glibc 2.42, systemd 258, Python 3.14 (JIT) and OpenSSL 3.5 (post-quantum). It includes no GUI, audio stack, or even the ‘less’ pager.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or FedoraHow-To Geek

Microsoft announced Azure Linux 4.0 at the Open Source Summit North America on May 18 2026 and demonstrated it at Build 2026. The distro is free, cloud-only, and tuned for Azure workloads, but the preview is not intended for production.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

Reviewers criticize the extreme minimalism—no desktop, no default user, and missing ‘less’ pager—making it unsuitable for general use. Azure Linux runs only on Azure; outside support is absent, and FIPS 140-3 certification remains pending.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

A HowToGeek reviewer installed Azure Linux 4.0 in VirtualBox via a custom text installer. The ISO lacks a GUI, creates no default user, and omits tools like Vim and ‘less’. Nginx installed but did not respond; SSH worked.

How-To Geek

Microsoft notes Azure Linux can technically run on non-Azure hardware, yet offers no official support. Pending FIPS 140-3 certification creates uncertainty for regulated sectors. Performance claims for dnf5 versus the older tdnf lack independent benchmarks.

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

> “Linux a cancer that attaches itself in an intellectual property sense to everything it touches.” — Steve Ballmer, former Microsoft CEO

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

> “The OS ships as a read-only image, so you cannot install packages, change settings, or make any changes on a running system.” — Azure Linux release notes

Microsoft called Linux a cancer, now ships its own free distro that’s nothing like Ubuntu or Fedora

> “A real Linux distro from Microsoft, for VMs and the cloud Azure Linux is a Linux distribution created by Microsoft.” — HowToGeek author

How-To Geek

> “The verdict Azure Linux might be good for tinkers, but not ready for prime time yet What struck me about Azure Linux is how ordinary it is.” — HowToGeek reviewer

How-To Geek