Microsoft Upgrades WSL2 to Linux 6.18 LTS — A Generational Leap for Windows-Linux Integration

# Microsoft Upgrades WSL2 to Linux 6.18 LTS — A Generational Leap for Windows-Linux Integration **April 18, 2026** | *Technology / Developer Tools* — Microsoft has released a significant update to the Windows Subsystem for Linux 2 (WSL2), upgrading its underlying kernel to the Linux 6.18 Long-Term Support (LTS) series. The new build, `linux-msft-wsl-6.18.20.1`, shipped on April 11, 2026, and marks the most substantial kernel evolution WSL2 has seen in years — one that signals a deliberate shift in how Microsoft intends to maintain and develop its Linux integration going forward. — ## From 6.6 to 6.18: Skipping Two LTS Cycles Until this release, WSL2 had been running on the Linux 6.6 LTS kernel — a version that is now two LTS cycles behind the current mainline. The jump to 6.18 LTS is therefore not a routine maintenance bump, but a meaningful catch-up that brings WSL2 substantially closer to the broader Linux ecosystem. A key benefit of the rebasing is that Microsoft has been able to shed a number of custom out-of-tree patches that had accumulated over the 6.6 era, including workarounds related to VirtIO PMEM support. Fewer proprietary patches means a leaner, more maintainable kernel — and one that is far easier to keep in sync with upstream Linux releases as they continue to roll out. — ## What’s New in the 6.18 Kernel for WSL2 The updated kernel configuration (`Kconfig`) introduces several practical improvements for WSL2 users: – **F2FS (Flash-Friendly File System) support** — useful for users working with flash storage or containers that benefit from F2FS’s design. – **ExFAT file system support** — somewhat surprisingly, this is the first time Microsoft has enabled its own widely-used ExFAT format within the WSL2 kernel. – **CAN bus protocol support** — relevant for embedded systems developers and automotive software engineers using WSL2 as a development environment. – **Joystick/game controller interface (`CONFIG_INPUT_JOYDEV`)** — opens the door for controller-related Linux development within WSL2. – **USB monitor support (`CONFIG_USB_MON`)** — enables USB traffic monitoring capabilities. – **`ANON_VMA_NAME` support** — a kernel feature that improves memory region debugging and observability. The ARM64 build also sees Kconfig alignment improvements, with FAT support now enabled parity with x86. — ## Part of a Larger Microsoft Commitment to WSL in 2026 This kernel update does not stand alone. It arrives as part of a broader wave of investment Microsoft is making in WSL during 2026. In March 2026, Microsoft outlined plans to significantly improve cross-environment file system performance — one of the most persistent pain points for WSL users. Accessing files on the Windows side via `/mnt/c` has historically been noticeably slower than native Linux I/O, particularly in projects with large numbers of small files. Microsoft is now actively working to reduce that latency and improve read/write speeds across the Windows–Linux boundary. Less than a year ago, at Microsoft Build 2025 in May, Microsoft took what many considered a historic step: it open-sourced the majority of WSL’s codebase, making it available on GitHub. The release included core command-line utilities (`wsl.exe`, `wslg.exe`), the background service managing the WSL virtual machine, and Linux-side daemons handling networking and port forwarding. A small number of components — specifically the WSL 1 kernel driver (`lxcore.sys`) and certain file system redirection drivers — remain proprietary, as they are deeply embedded in the Windows image. The open-sourcing fulfilled a request that had been sitting open in WSL’s GitHub issue tracker since the very beginning: Issue #1, “Will this be Open Source?” — filed nearly a decade ago. — ## A Note on What WSL2 Actually Is It is worth clarifying a common misconception: WSL2 does not run Linux “directly” on Windows hardware without any virtualization layer. Under the hood, WSL2 uses a lightweight Hyper-V virtual machine to host the Linux kernel. This approach — introduced when WSL2 launched with Windows 10 version 2004 in 2019 — was a deliberate architectural choice that delivers full Linux syscall compatibility and near-native I/O performance within the Linux file system. The experience feels seamless to most users, but it is technically a lightweight VM, not bare metal Linux. WSL2 also runs on both Windows 10 and Windows 11, not Windows 11 exclusively. — ## How to Update Updating to the new kernel is straightforward. Open PowerShell as administrator and run: “` wsl –update “` To try pre-release builds: “` wsl –update –pre-release “` After updating, restart WSL to load the new kernel: “` wsl –shutdown “` You can confirm the active kernel version by running the following inside any WSL distribution: “` uname -r “` A version string beginning with `6.18` confirms the update is active. — ## The Bigger Picture WSL2 has quietly matured into a serious development platform. Web developers, backend engineers, DevOps practitioners, and data scientists all rely on it daily — Docker Desktop on Windows is itself heavily dependent on WSL2. Visual Studio Code integrates with it natively. And with the kernel now tracking a modern LTS baseline, Microsoft appears committed to keeping that foundation fresh rather than letting it drift behind for years at a time. The combination of the open-sourced codebase, the 2026 performance roadmap, and this kernel update paints a coherent picture: Microsoft is treating WSL2 not as a niche compatibility layer, but as a first-class platform for the millions of developers who need Linux tooling without leaving Windows behind. — *Sources: Phoronix, Microsoft WSL2-Linux-Kernel GitHub, Windows Developer Blog, Windows Latest, Bleeping Computer, Heise Online*

Microsoft has released a significant update to the Windows Subsystem for Linux 2 (WSL2), upgrading its underlying kernel to the Linux 6.18 Long-Term Support (LTS) series.