CCleaner, one of the enormously popular free PC optimization suites for Windows, is now being detected as Potentially Unwanted Application (PUA) on Windows 10 after a recent update to Windows Defender platform.

CCleaner basically allows you to optimize your system using its scan checks for cookies, cached files, downloaded files in all the major browsers, and it also includes a comprehensive registry cleaner.

In a surprising move, Windows Defender Antivirus has started flagging CCleaner utility as Potentially Unwanted App.

Potentially Unwanted Application (PUA) protection is a feature that allows Windows Defender Antivirus to detect and block unwanted apps.

PUA alert

According to user reports, Windows Defender flags CCleaner as a Potentially Unwanted Program with alert level low, but the CCleaner is not detected as a threat to the system and users can still manually allow the app to run on their systems.

In support documentation, Microsoft noted that PUAs are not categorized as viruses, malware or other types of threats, but such as apps could “adversely affect endpoint performance or use” and offer to install other apps that qualify as PUA.

Windows Defender also flags apps with ‘poor reputation’ as potentially unwanted program due to “certain kinds of undesirable behaviour”.

Microsoft says CCleaner installer includes certain software, such as the Google Toolbar and Avast. Bundling of software, especially products from other providers that negatively impact the user experience fall under the category of PUA or PUP.

CCleaner installer has been found bundling the following apps:

  • Google Chrome
  • Google Toolbar
  • Avast Free Antivirus
  • AVG Antivirus Free

It appears that only the free version of CCleaner is detected as PUA by Windows Defender and Windows 10 will block CCleaner until the installer itself comes with such software bundled by default.

CCleaner is in touch with Microsoft

Avast has told us that they are in discussions with Microsoft to resolve this issue as soon as possible.

“We have discovered that Windows Defender has recently classified the free version of CCleaner and some other of our tools and partners’ tools as “Potentially Unwanted Software”. Our products and our partners’ products are genuine and so we are in discussions with Microsoft to resolve this issue as soon as we can,” a spokesperson from Avast told us.

If Windows Defender has blocked CCleaner on your system and you know that it can be trusted, you can allow the app under Windows Security > Virus & threat protection > Threat history.

About The Author

Mayank Parmar

Mayank Parmar is Windows Latest's owner, Editor-in-Chief and entrepreneur. Mayank has been in tech journalism for over seven years and has written on various topics, but he is mostly known for his well-researched work on Microsoft's Windows. His articles and research works have been referred to by CNN, Business Insiders, Forbes, Fortune, CBS Interactive, Microsoft and many others over the years.