CVE-2026-83839

EUVD-2026-99378
Time-of-check time-of-use (toctou) race condition in Windows Hyper-V allows an authorized attacker to elevate privileges locally.
TOCTOU
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
NISTPrimary
7 HIGH
LOCAL
HIGH
LOW
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Awaiting analysis
This vulnerability is currently awaiting analysis.
Base Score
CVSS 3.x
EPSS Score
Percentile: 8.36%
Windows Releases
Platform
Version
Windows 10
1809 (x64, x86)
KB5126651
21H2 (arm64, x64, x86)
KB5126657
22H2 (arm64, x64, x86)
KB5126657
Windows 11
23H2 (arm64, x64)
KB5126653
24H2 (arm64, x64)
KB5127648
25H2 (arm64, x64)
KB5127648
26H1 (arm64, x64)
KB5127646
26H2 (arm64, x64)
KB5127648
Windows Server 2019
Server Core
KB5126651
Standard
KB5126651
Windows Server 2022
Server Core
KB5126655
Standard
KB5126655
Windows Server 2025
Server Core
KB5126646
Standard
KB5126646
Common Weakness Enumeration
References
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83839