Windows 10 VPN Flaw Gets Emergency Fix Amidst Coronavirus Crisis

Microsoft has released an emergency fix for a bug in a recent Windows 10 patch that had caused some users to experience problems when connecting to the internet over a virtual private network (VPN).

But some users said that in some cases the patch caused problems when connecting to Wi-Fi networks.

The issue arrived at an inopportune time, as large portions of the workforce in a number of countries are currently restricted to working remotely during the coronavirus crisis.

Microsoft said last week that the connectivity issue was caused by KB4535996, an optional cumulative update deployed in late February.

VPN problem

It can prevent any software that uses WinHTTP or WinInet from connecting to the internet, especially when a VPN is in use.

The problem often manifested when connecting to, or disconnecting from, a VPN, Microsoft said.

The software affected includes Office 365, Microsoft Outlook, Microsoft Teams, Microsoft’s web browsers and other software.

The bug also causes the system to display incorrect internet connectivity information, Microsoft said.

“Devices using a manual or auto-configured proxy, especially with a virtual private network (VPN), might show limited or no internet connection status in the Network Connectivity Status Indicator (NCSI) in the notification area,” Microsoft said in an advisory.

“This might happen when connected or disconnected to a VPN or after changing state between the two.

“Devices with this issue, might also have issues reaching the internet using applications that use WinHTTP or WinInet.

“Examples of apps that might be affected on devices in this state are as follows but not limited to Microsoft Teams, Microsoft Office, Office365, Outlook, Internet Explorer 11, and some version of Microsoft Edge.”

Emergency fix

Microsoft said the newly issued out-of-band fix, KB4554364, fixes the underlying issue.

The description for the patch says that it addresses “an issue that might display a limited or no internet connection status in the notification area on devices that use a manual or auto-configured proxy, especially with a virtual private network (VPN).

“Additionally, this issue might prevent some devices from connecting to the internet using applications that use WinHTTP or WinINet.”

The optional is not being offered over Windows Update, and Microsoft advised users to apply it only if they are affected by the problem.

The company issued different manually installable versions of the patch for Windows 10, versions 1909, 1903, 1809, 1803 and 1709.

Some users said the update caused issues with connecting to Wi-Fi networks, causing the system to display an error message.

The problem, which has  not been confirmed by Microsoft, can reportedly be fixed by uninstalling the KB4554364 update.