Description

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

INFO

Published Date :

2026-02-10T17:51:44.627Z

Last Modified :

2026-02-11T19:49:08.352Z

Source :

microsoft
AFFECTED PRODUCTS

The following products are affected by CVE-2026-21240 vulnerability.

Vendors Products
Microsoft
  • Windows 10 1809
  • Windows 10 21h2
  • Windows 10 21h2
  • Windows 10 22h2
  • Windows 10 22h2
  • Windows 11 22h3
  • Windows 11 23h2
  • Windows 11 23h2
  • Windows 11 24h2
  • Windows 11 24h2
  • Windows 11 25h2
  • Windows 11 25h2
  • Windows 11 26h1
  • Windows 11 26h1
  • Windows Server 2019
  • Windows Server 2019 (server Core Installation)
  • Windows Server 2022
  • Windows Server 2022, 23h2 Edition (server Core Installation)
  • Windows Server 2022 23h2
  • Windows Server 2025
  • Windows Server 2025 (server Core Installation)
  • Windows Server 23h2
REFERENCES

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-21240.

URL Resource
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21240 cve-icon cve-icon
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CVSS Vulnerability Scoring System

Detailed values of each vector for above chart.
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact