CVE-2026-21236
Analyzed
Analyzed - Analysis Complete
Heap-Based Buffer Overflow in Windows WinSock Driver Elevates Privileges
Vulnerability report for CVE-2026-21236, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-02-10
Last updated on: 2026-02-11
Assigner: Microsoft Corporation
Description
Description
Heap-based buffer overflow in Windows Ancillary Function Driver for WinSock 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_server_2012 | r2 |
| microsoft | windows_server_2012 | * |
| microsoft | windows_10_1607 | to 10.0.14393.8868 (exc) |
| microsoft | windows_10_1607 | to 10.0.14393.8868 (exc) |
| microsoft | windows_10_1809 | to 10.0.17763.8389 (exc) |
| microsoft | windows_server_2016 | to 10.0.14393.8868 (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-122 | A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). |
| CWE-787 | The product writes data past the end, or before the beginning, of the intended buffer. |
