A security researcher found that URLs visited in "InPrivate Mode" on Windows 10's default browser, Edge, can still be found as they are stored in a separate folder on the hard drive. The researcher reported the issue to Microsoft in October last year already, but the company hasn't released a fix yet.
He discovered that the URLs of visited pages are stored in a separate folder on the hard drive, including the ones visited in InPrivate mode.
This only includes the browsing history, not the actual contents of the pages. To generate some additional attention after he received no replies from Microsoft he reported the issue to TheVerge which could easily reproduce the issue and wrote about it.
Microsoft has now told the the tech site that it knows about the issue and is working on a solution.