Windows 10 still on 1 in 6 PCs — nearly 3x more active security flaws than Win 11

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Migration is slowing down as the more difficult cases remain on the legacy OS

Windows 10 devices are said to have 3x as many active CVEs

Technical limitations and physical upgrades aren't a major issue

According to new Lansweeper data, as many as 16.9% of Windows client devices, which equates roughly to a total of one in six overall, still runs Windows 10.

While Windows 11 now accounts for 78.8% of installs and Windows 10's market share has fallen from about 50% in mid-2025, Lansweeper warns the migration is starting to slow down, implying the remaining Windows 10 market share could show no signs of going anywhere.

And that's a worrying state of affairs, because the average Windows 10 device has around 3x as many active CVEs (1,903) as a Windows 11 devices (652).

Windows 10 market share could be a security nightmare

Additionally, around two-thirds of the active CVEs on Windows 10 are rated high or critical, and the rate of vulnerabilities known to be exploitable is around 1.7x higher than on Windows 11.

The report notes that Microsoft's Extended Security Updates (ESU) program buys some breathing room, protecting consumers until October 2027 and paying commercial customers until October 2028.

Healthcare and pharmaceuticals (23%), consumer and retails (23%) and manufacturing (18%) are among the industries most likely to still be running Windows 10, with SMBs (21.4%) more likely to be running the outgoing OS compared with enterprises (16.6%).

Lansweeper also revealed that technical limitations aren't necessarily to blame, with only 2.8% of the Windows 10 devices it analyzed failing Windows 11's hardware requirements.

More broadly, the report warns that nearly one-fifth (18.7%) of the entire Windows landscape it monitors runs end-of-life operating systems like Windows 7, Windows 8.1 and Windows XP.

The report concludes that, while many users have now upgraded to the latest OS, the remaining estate is smaller but disproportionately more difficult, expensive or risky to update. But with ESU programs soon running to an end, deeper considerations into leaving Windows 10 should be made.