Windows 10 Version 21H2 vulnerabilities

393 known vulnerabilities in Windows 10 Version 21H2 from Microsoft. 373 are rated high or critical, and 99 have been exploited in real attacks. Each entry lists the affected versions and the release that fixes it, where the vendor has published one.

Latest first

• 7.0 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-27918Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Shell allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-27911Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows User Interface Core allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-26174Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Server Update Service allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-26173Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 21H2: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-26172Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Push Notifications allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-26168Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-26167Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Push Notifications allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20930Apr 14, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Improper Validation of Specified Type of Input

  CVE-2026-25179Mar 10, 2026Microsoft

  Improper validation of specified type of input in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

• 8.8 High severity

  Windows 10 Version 1607: Improper Restriction of Names for Files and Other Resources

  CVE-2026-25177Mar 10, 2026MicrosoftEPSS 1.35%

  Improper restriction of names for files and other resources in Active Directory Domain Services allows an authorized attacker to elevate privileges over a network.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-24296Mar 10, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Device Association Service allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-24295Mar 10, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Device Association Service allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1607: Incorrect Permission Assignment for Critical Resource

  CVE-2026-24291Mar 10, 2026MicrosoftEPSS 4.61%

  Incorrect permission assignment for critical resource in Windows Accessibility Infrastructure (ATBroker.exe) allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-23671Mar 10, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Bluetooth RFCOM Protocol Driver allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-23668Mar 10, 2026MicrosoftEPSS 3.87%

  Concurrent execution using shared resource with improper synchronization ('race condition') in Microsoft Graphics Component allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Microsoft Windows Improper Privilege Management Exploited

  CVE-2026-21533Feb 10, 2026MicrosoftEPSS 4.33%

  Improper privilege management in Windows Remote Desktop allows an authorized attacker to elevate privileges locally.

• 6.2 Medium severity

  Microsoft Windows NULL Pointer Dereference Exploited

  CVE-2026-21525Feb 10, 2026MicrosoftEPSS 5.04%

  Null pointer dereference in Windows Remote Access Connection Manager allows an unauthorized attacker to deny service locally.

• 7.8 High severity

  Microsoft Windows Type Confusion Exploited

  CVE-2026-21519Feb 10, 2026MicrosoftEPSS 2.57%

  Access of resource using incompatible type ('type confusion') in Desktop Window Manager allows an authorized attacker to elevate privileges locally.

• 8.8 High severity

  Microsoft MSHTML Framework Protection Mechanism Failure Exploited

  CVE-2026-21513Feb 10, 2026MicrosoftEPSS 15.9%

  Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network.

• 8.8 High severity

  Microsoft Windows Shell Protection Mechanism Failure Exploited

  CVE-2026-21510Feb 10, 2026MicrosoftEPSS 61.2%

  Protection mechanism failure in Windows Shell allows an unauthorized attacker to bypass a security feature over a network.

• 7.0 High severity

  Windows 10 Version 21H2: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-21237Feb 10, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-21234Feb 10, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Connected Devices Platform Service allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-21231Feb 10, 2026MicrosoftEPSS 2.52%

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Kernel allows an authorized attacker to elevate privileges locally.

• 7.5 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20934Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.

• 7.5 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20926Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.

• 7.5 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20921Jan 13, 2026MicrosoftEPSS 1.18%

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.

• 7.5 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20919Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20918Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.5 High severity

  Windows 10 Version 1607: NULL Pointer Dereference

  CVE-2026-20875Jan 13, 2026MicrosoftEPSS 1.54%

  Null pointer dereference in Windows Local Security Authority Subsystem Service (LSASS) allows an unauthorized attacker to deny service over a network.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20874Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20873Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20869Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Local Session Manager (LSM) allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20867Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20866Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1809: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20861Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Management Services allows an authorized attacker to elevate privileges locally.

• 7.8 High severity

  Windows 10 Version 1607: Access of Resource Using Incompatible Type

  CVE-2026-20860Jan 13, 2026MicrosoftEPSS 8.28%

  Access of resource using incompatible type ('type confusion') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

• 7.4 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20853Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows WalletService allows an unauthorized attacker to elevate privileges locally.

• 7.5 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20848Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Windows SMB Server allows an authorized attacker to elevate privileges over a network.

• 7.0 High severity

  Windows 10 Version 1607: Concurrent Execution using Shared Resource with Improper Synchronization

  CVE-2026-20836Jan 13, 2026Microsoft

  Concurrent execution using shared resource with improper synchronization ('race condition') in Graphics Kernel allows an authorized attacker to elevate privileges locally.

• 7.0 High severity

  Windows 10 Version 1607: Time-of-check Time-of-use (TOCTOU) Race Condition

  CVE-2026-20831Jan 13, 2026Microsoft

  Time-of-check time-of-use (toctou) race condition in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.