{
"title": "WSL 2.7.7 and 2.7.5 Preview Bring Linux Kernel 6.18, VHD Access Fixes, and WSLg Package Update",
"content": "Microsoft has pushed out not one but two new preview builds of Windows Subsystem for Linux — version 2.7.5 and 2.7.7 — bringing an updated Linux kernel, long-awaited fixes for VHD access, and a packaging change for WSLg. These releases may appear minor at first glance, but the kernel bump to 6.18 signals a significant under-the-hood refresh that WSL enthusiasts will want to examine closely. Both builds are currently available only on the preview track, requiring users to opt in with wsl --update --pre-release or an MSI download from the official GitHub repository.

The Kernel Upgrade: Linux 6.18 Comes to WSL2

WSL 2 uses a custom Linux kernel that Microsoft ships and updates independently of the Windows release cycle. With these preview releases, that kernel jumps to version 6.18 — a notable leap from the previous 5.15.x- or 6.1.x-series kernels many users were running. While Microsoft hasn’t published a detailed changelog, the move to a 6.18 base likely pulls in months of upstream Linux improvements. That means better hardware support, updated drivers, security patches, and performance optimizations. For developers running databases, compilers, or network-heavy workloads inside WSL 2, a newer kernel can translate into measurable gains, especially in I/O and memory management.

But there’s a catch: WSL kernels are custom-tuned. Microsoft applies its own patches on top of mainline to ensure tight integration with Windows, support for Plan 9 filesystem sharing, and WSL-specific drivers. So users shouldn’t expect a vanilla 6.18 kernel; instead, they’re getting a Microsoft-curated version that balances upstream freshness with Windows compatibility. Still, the jump to 6.18 suggests the team is keeping pace with modern Linux developments, which is encouraging.

From a Linux perspective, the 6.18 kernel itself is a recent stable release that brings a host of new features. Though Microsoft trims many drivers and subsystems that aren’t relevant to WSL, improvements like enhanced CPU scheduler performance, better power management, and advanced networking protocols can indirectly benefit WSL workloads. Filesystem performance, in particular, could see gains thanks to ongoing work on the ext4 driver and the VFS layer. For WSL, which relies heavily on ext4 for its VHD-mounted root filesystems, every bit of I/O optimization matters.

Microsoft has a history of carefully porting upstream improvements while keeping their own modifications minimal. The 6.18 kernel in WSL 2.7.x likely includes all security patches up to a recent stable tag, closing vulnerabilities that could affect containers, networking, or local privilege escalation. If you’re running containers inside WSL (with Docker or Podman), this kernel refresh could provide better isolation and compatibility with newer container images that expect a modern kernel.

VHD Access Fixes: Solving Disk Headaches

One of the most persistent pain points for WSL 2 users has been VHD access. WSL 2 stores Linux files inside a virtual hard disk (VHD) that grows dynamically. Mounting, resizing, or accessing that VHD from Windows tools often led to errors, corruption risks, or permission issues. The 2.7.5 and 2.7.7 releases specifically address VHD access problems, according to the release notes. While Microsoft hasn’t detailed every fix, improved VHD handling could mean smoother wsl --mount operations, better interoperability with disk management utilities, and fewer “disk is in use” errors when moving distros between machines.

For power users who frequently back up or clone WSL environments, these fixes reduce friction. No longer will you need to rely on community workarounds to safely attach a WSL VHD to Windows. And for those who run WSL instances on external drives, the enhancements may lead to more reliable performance.

Historically, WSL 2’s VHD architecture has been a double-edged sword. It provides full Linux filesystem fidelity, but mounting the raw VHD from Windows Explorer or third-party tools could lock the file or cause inconsistent states. Some users reported that resizing the VHD with wsl --shrink would fail silently or leave disk space unclaimed. With these updates, Microsoft appears to have addressed the underlying volume management. Early testers on Reddit and other forums note that the wsl --mount --vhd command now works reliably with removable media, and Windows Disk Management no longer throws errors when viewing the VHD.