Canonical Launches Ubuntu Core 26, Its Latest Snap-Powered Immutable Operating System
Core distribution comes with some major improvements since 2024, including a big reduction in OTA update sizes.
Canonical has announced the release of Ubuntu Core 26, the latest in its cut-down immutable Linux distribution originally developed with a focus on the Internet of Things (IoT).
"Ten years ago, Ubuntu Core pioneered a new OS [Operating System] security model, where every component is strictly confined, transactionally updated, and independently verifiable," says Canonical's vice president of Ubuntu engineering Jon Seager of the distribution. "Today, that approach is reflected in emerging industry standards. With Ubuntu Core 26, we continue to deliver the foundation that critical infrastructure operators need to meet the Cyber Resilience Act, run attested, immutable edge AI [Artificial Intelligence] workloads, and manage devices securely at scale."
Ubuntu Core is, as the name implies, built atop Canonical's popular Ubuntu Linux, which is in turn derived from the long-running Debian Linux distribution. The difference: formerly known as Snappy Ubuntu Core, the distribution focuses on sandboxing software using Canonical's "snap" packaging format and Snap Store distribution servers — securing an immutable base operating system from modification by the apps running atop it.
The new release comes with the promise of dramatically improved efficiency for over-the-air software updates, with Canonical claiming that changes to the snap-delta changes-only format mean a reduction in size of between 50 and 90% for "most snaps," with the Core base snap itself dropping from 16MB to just 1.5MB. The number of reboots required during updates has also been dropped, cutting installation times.
A more core change is the shift to a new Chisel-based build system, designed to improved the traceability of dependencies. "Every file in the filesystem can be attributed to its originating slice and source package, improving the accuracy of integrity checks and vulnerability triage," the company claims. "This contrasts with approaches like Yocto builds, where provenance and dependency closure are largely implicit in layered recipes and post-processing. The new build system also contributes to a 7% reduction in base image size."
Other improvements include integration with Canonical's Juju- and Kubernetes-based Observability Stack platform, general availability of the snap "components" distribution feature introduced in Ubuntu Core 24 for NVIDIA's graphics driver packages, and support for running multiple graphical applications on a single display with hardware acceleration in an updated Ubuntu Frame.
More information is available on the Ubuntu Core site, along with instructions for building an Ubuntu Core image.