This content is taken from official support documentation.
https://learn.microsoft.com/ko-kr/windows/release-health/status-windows-11-25h2#3801msgdesc
Microsoft has received reports of an issue where some Samsung device models are unable to access the C: drive after installing KB5077181 (security update) and subsequent updates released in February 2026. Users may experience a "C:\ Access Denied" error that blocks file access and prevents the launch of applications such as Outlook, Office apps, web browsers, system utilities, and Quick Assist.
Affected devices experience issues when users perform common tasks such as file access, application launches, or administrative tasks. In some cases, users may be unable to collect logs due to privilege escalation, update removal, or permission errors.
This issue has been reported in various regions, including Brazil, Portugal, Korea, and India, and is primarily observed on Samsung Galaxy Book 4 and other Samsung consumer devices. While the root cause is still under investigation, it may be related to the Samsung Share application.
