Windows system remain vulnerable to downgrade exploit.

Despite issuing multiple patches, Windows systems remain vulnerable to a downgrade exploit. Researcher found that certain files that should be unchangeable can be changed under certain circumstances. During those times, the files can be changed such that the Windows kernel can be downgraded without the owner noticing.

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https://cybernews.com/security/windows-can-still-be-downgraded-to-vulnerable-versions/