Instituto Nacional de ciberseguridad. Sección Incibe
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CVE-2026-21240

Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
10/02/2026
Last modified:
11/02/2026

Description

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

Impact

Vector 3.x
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.80 HIGH
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): Low
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x
7.80
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:* 10.0.17763.8389 (excluding)
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:* 10.0.17763.8389 (excluding)
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:* 10.0.19044.6937 (excluding)
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:* 10.0.19044.6937 (excluding)
cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:* 10.0.19044.6937 (excluding)
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:* 10.0.19045.6937 (excluding)
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:* 10.0.19045.6937 (excluding)
cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:* 10.0.19045.6937 (excluding)
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:* 10.0.22631.6649 (excluding)
cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:* 10.0.22631.6649 (excluding)
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:* 10.0.26100.7781 (excluding)
cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:* 10.0.26100.7781 (excluding)
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:* 10.0.26200.7781 (excluding)
cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:* 10.0.26200.7781 (excluding)
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:* 10.0.17763.8389 (excluding)

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools