CVE-2026-21240
Analyzed
Analyzed - Analysis Complete
TOCTOU Race Condition in Windows HTTP.sys Enables Local Privilege Escalation
Publication date: 2026-02-10
Last updated on: 2026-02-11
Assigner: Microsoft Corporation
Description
Description
Time-of-check time-of-use (toctou) race condition in Windows HTTP.sys allows an authorized attacker to elevate privileges locally.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| microsoft | windows_10_1809 | to 10.0.17763.8389 (exc) |
| microsoft | windows_server_2019 | to 10.0.17763.8389 (exc) |
| microsoft | windows_server_2022 | to 10.0.20348.4711 (exc) |
| microsoft | windows_server_2025 | to 10.0.26100.32313 (exc) |
| microsoft | windows_11_24h2 | to 10.0.26100.7781 (exc) |
| microsoft | windows_11_24h2 | to 10.0.26100.7781 (exc) |
| microsoft | windows_11_23h2 | to 10.0.22631.6649 (exc) |
| microsoft | windows_11_23h2 | to 10.0.22631.6649 (exc) |
| microsoft | windows_11_25h2 | to 10.0.26200.7781 (exc) |
| microsoft | windows_11_25h2 | to 10.0.26200.7781 (exc) |
| microsoft | windows_server_2022_23h2 | to 10.0.25398.2149 (exc) |
| microsoft | windows_10_22h2 | to 10.0.19045.6937 (exc) |
| microsoft | windows_10_22h2 | to 10.0.19045.6937 (exc) |
| microsoft | windows_10_22h2 | to 10.0.19045.6937 (exc) |
| microsoft | windows_10_21h2 | to 10.0.19044.6937 (exc) |
| microsoft | windows_10_21h2 | to 10.0.19044.6937 (exc) |
| microsoft | windows_10_21h2 | to 10.0.19044.6937 (exc) |
| microsoft | windows_10_1809 | to 10.0.17763.8389 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-367 | The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. |
