CVE-2026-21237
Race Condition in Windows Subsystem for Linux Enables Local Privilege Escalation
Publication date: 2026-02-10
Last updated on: 2026-02-11
Assigner: Microsoft Corporation
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| 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) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-416 | The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. |
| CWE-362 | The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. |
Attack-Flow Graph
AI Powered Q&A
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
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How can this vulnerability be detected on my network or system? Can you suggest some commands?
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Can you explain this vulnerability to me?
This vulnerability is a race condition caused by concurrent execution using a shared resource with improper synchronization in the Windows Subsystem for Linux.
It allows an authorized attacker to elevate their privileges locally on the affected system.
How can this vulnerability impact me? :
The vulnerability can allow an authorized local attacker to elevate their privileges, potentially gaining higher-level access than intended.
This can lead to unauthorized actions, such as modifying system settings, accessing sensitive data, or installing malicious software.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, it is recommended to apply the security updates provided by Microsoft for Windows Subsystem for Linux as soon as they become available.
Since the vulnerability involves a race condition allowing local privilege escalation, limiting local user access and ensuring that only authorized users have access to the system can reduce risk.