CVE-2026-20809

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2026-20809
Time-of-check time-of-use (toctou) race condition in Windows Kernel Memory allows an authorized attacker to elevate privileges locally.

7.8 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 1.8 / Impact : 5.9

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20809 Vendor Advisory
Configurations

Configuration 1 (hide)

OR cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*
History

14 Jan 2026, 20:11

Type Values Removed Values Added
CPE cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
First Time Microsoft windows 11 24h2
Microsoft windows 11 25h2
Microsoft windows Server 2022
Microsoft
Microsoft windows Server 2016
Microsoft windows Server 2022 23h2
Microsoft windows 10 1607
Microsoft windows Server 2012
Microsoft windows 10 1809
Microsoft windows 10 21h2
Microsoft windows 11 23h2
Microsoft windows 10 22h2
Microsoft windows Server 2019
Microsoft windows Server 2025
References () https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20809 - () https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20809 - Vendor Advisory

13 Jan 2026, 18:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-01-13 18:16

Updated : 2026-01-14 20:11

NVD link : CVE-2026-20809

Mitre link : CVE-2026-20809

CVE.ORG link : CVE-2026-20809

JSON object : View

Products Affected

microsoft

  • windows_server_2025
  • windows_10_1809
  • windows_server_2012
  • windows_10_22h2
  • windows_server_2022_23h2
  • windows_server_2019
  • windows_server_2022
  • windows_10_1607
  • windows_11_24h2
  • windows_server_2016
  • windows_11_23h2
  • windows_11_25h2
  • windows_10_21h2
CWE
CWE-122

Heap-based Buffer Overflow

CWE-367

Time-of-check Time-of-use (TOCTOU) Race Condition