CVE-2026-21240
Windows HTTP.sys Elevation of Privilege Vulnerability
At a glance
- Severity
- HIGH 7.8
- EPSS
- EPSS 0.28 % · percentile 20 (2026-10-27)
- State
- PUBLISHED
- Published
- Updated
- Assigner
- microsoft
- NVD status
- Analyzed
Description
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
Scores
| Version | Score | Vector | Scored by |
|---|
| CVSS 3.1 | HIGH 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C | microsoft |
| CVSS 3.1 | HIGH 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD · secure@microsoft.com (Secondary) |
| CVSS 3.1 | HIGH 7.0 | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD · nvd@nist.gov (Primary) |
Weaknesses (CWE)
European references
CERT-FR advisories
Affected configurations (NVD CPE)
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:* < 10.0.17763.8389cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:* < 10.0.17763.8389cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:* < 10.0.19044.6937cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:* < 10.0.19044.6937cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:* < 10.0.19044.6937cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:* < 10.0.19045.6937cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:* < 10.0.19045.6937cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:* < 10.0.19045.6937cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:* < 10.0.22631.6649cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:* < 10.0.22631.6649cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:* < 10.0.26100.7781cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:* < 10.0.26100.7781cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:* < 10.0.26200.7781cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:* < 10.0.26200.7781cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:* < 10.0.17763.8389cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:* < 10.0.20348.4711cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:* < 10.0.25398.2149cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:* < 10.0.26100.32313
Affected products
References
Sources
