Windows 11 KB5072033 Breaks WSL Networking With VPNs, Microsoft Confirms
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Microsoft’s December 2025 Patch Tuesday update for Windows 11, KB5072033, is causing new problems after its release on December 9, 2025. While the update delivers important security fixes and system improvements, Microsoft has now confirmed multiple unresolved and newly discovered issues.
WSL loses network access when using VPNs in KB5072033
Microsoft confirmed a bug affecting Windows Subsystem for Linux (WSL) when users enable mirrored networking mode alongside certain third-party VPNs. The issue impacts popular solutions like Cisco Secure Client (formerly AnyConnect) and OpenVPN.
Affected systems lose network connectivity inside WSL, triggering errors such as “No route to host.” These errors block access to services and network resources while the VPN remains active.
Microsoft explained that the problem occurs because the VPN’s virtual network interface fails to respond to ARP (Address Resolution Protocol) requests. As a result, network traffic inside WSL cannot route correctly.
Home and Pro users rarely encounter this issue, according to Microsoft. Enterprise environments face higher risk due to heavier VPN and WSL usage.
File Explorer flashing fix remains incomplete
KB5072033 aimed to fix a visual bug that caused white flashes in File Explorer when users enabled dark mode or opened new tabs. Microsoft acknowledged that the fix remains incomplete.
Some users still report brief white flashes when opening new File Explorer tabs, despite the update being installed. This contradicts earlier expectations that the issue was fully resolved.
Installation errors and performance concerns
Several users also report installation failures with error code 0x800f0991. In addition, KB5072033 may impact performance by enabling extra background services, which could affect lower-end systems.
Microsoft acknowledged the WSL and VPN bug and confirmed that a fix will not arrive before the January 2026 Patch Tuesday update, expected around January 13, 2026.
Until then, enterprise users relying on WSL and VPNs may want to delay deployment or adjust configurations.
Hopefully, Microsoft addresses these issues quickly in upcoming updates.
Via Windows Latest
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