Unrated severityNVD Advisory· Published Feb 10, 2026· Updated Apr 10, 2026

Windows HTTP.sys Elevation of Privilege Vulnerability

CVE-2026-21240

Description

Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.

Microsoft/Windows 10 1809cpe-rescue
Range: 10.0.17763.0
Microsoft/Windows 10 1607cpe-rescue2 versions
10.0.19044.0+ 1 more
- (no CPE)range: 10.0.19044.0
- (no CPE)range: 10.0.19045.0
Microsoft/Windows 11 version 22H3v5
Range: 10.0.22631.0
Microsoft/Windows 11 23h2cpe-rescue
Range: 10.0.22631.0
Microsoft/Windows 11 24h2cpe-rescue
Range: 10.0.26100.0
Microsoft/Windows 11 25h2cpe-rescue
Range: 10.0.26200.0
Microsoft/Windows 11 26h1cpe-rescue
Range: 10.0.28000.0
Microsoft/Windows Server 2019cpe-rescue
Range: 10.0.17763.0
Microsoft/Windows Server 2019 (Server Core installation)v5
Range: 10.0.17763.0
Microsoft/Windows Server 2003cpe-rescue
Range: 10.0.20348.0
Microsoft/Windows Server 2022, 23H2 Edition (Server Core installation)v5
Range: 10.0.25398.0
Microsoft/Windows Server 2025cpe-rescue
Range: 10.0.26100.0
Microsoft/Windows Server 2025 (Server Core installation)v5
Range: 10.0.26100.0

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