CVE-2026-21241
published 2026-02-10CVE-2026-21241: Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
PriorityP342high7CVSS 3.1
AVLACHPRLUINSUCHIHAH
EPSS
2.49%
82.9th percentile
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Affected
24 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_11_23h2 | < 10.0.22631.6649 | 10.0.22631.6649 |
| microsoft | windows_11_24h2 | < 10.0.26100.7781 | 10.0.26100.7781 |
| microsoft | windows_11_25h2 | < 10.0.26200.7781 | 10.0.26200.7781 |
| microsoft | windows_11_version_22h3 | >= 10.0.22631.0 < 10.0.22631.6649 | 10.0.22631.6649 |
| microsoft | windows_11_version_23h2 | >= 10.0.22631.0 < 10.0.22631.6649 | 10.0.22631.6649 |
| microsoft | windows_11_version_24h2 | >= 10.0.26100.0 < 10.0.26100.7840 | 10.0.26100.7840 |
| microsoft | windows_11_version_25h2 | >= 10.0.26200.0 < 10.0.26200.7840 | 10.0.26200.7840 |
| microsoft | windows_11_version_26h1 | >= 10.0.28000.0 < 10.0.28000.1575 | 10.0.28000.1575 |
| microsoft | windows_server_2022 | < 10.0.20348.4711 | 10.0.20348.4711 |
| microsoft | windows_server_2022 | >= 10.0.20348.0 < 10.0.20348.4773 | 10.0.20348.4773 |
| microsoft | windows_server_2022_23h2 | < 10.0.25398.2149 | 10.0.25398.2149 |
| microsoft | windows_server_2025 | < 10.0.26100.32313 | 10.0.26100.32313 |
| microsoft | windows_server_2025 | >= 10.0.26100.0 < 10.0.26100.32370 | 10.0.26100.32370 |
| msrc | windows_11_version_23h2_for_arm64-based_systems | — | — |
| msrc | windows_11_version_23h2_for_x64-based_systems | — | — |
| msrc | windows_11_version_24h2_for_arm64-based_systems | — | — |
| msrc | windows_11_version_24h2_for_x64-based_systems | — | — |
| msrc | windows_11_version_25h2_for_arm64-based_systems | — | — |
| msrc | windows_11_version_25h2_for_x64-based_systems | — | — |
| msrc | windows_11_version_26h1_for_arm64-based_systems | — | — |
| msrc | windows_11_version_26h1_for_x64-based_systems | — | — |
| msrc | windows_server_2022 | — | — |
| msrc | windows_server_2022_23h2_edition | — | — |
| msrc | windows_server_2025 | — | — |
CVSS provenance
nvdv3.17.0HIGHCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_msrc7.0HIGH
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GHSA
GHSA-3g4j-rmgh-9r5p: Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally
ghsa_unreviewed·2026-02-10
CVE-2026-21241 [HIGH] CWE-416 GHSA-3g4j-rmgh-9r5p: Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Microsoft
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
vendor_msrc·2026-02-10·CVSS 7.0
CVE-2026-21241 [HIGH] CWE-416 Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
Description: Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
FAQ: According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability?
For an attacker to exploit this vulnerability, they would need to have knowledge of a specific operation that triggers a memory allocation failure, specifically a use after free.
FAQ: What privileges could be gained by an attacker who successfully exploited this vulnerability?
An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.
Windows Ancillary Function Driver for WinSock: Windows Ancillary Function Driver for WinSock
No detection rules found.
No public exploits indexed.
Sophos
February’s Patch Tuesday assumes battle stations
blogs_sophos·2026-02-13
February’s Patch Tuesday assumes battle stations
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Qualys
Microsoft and Adobe Patch Tuesday, February 2026 Security Update Review
blogs_qualys·2026-02-10
Microsoft and Adobe Patch Tuesday, February 2026 Security Update Review
## Table of Contents
Microsoft Patch Tuesday forFebruary2026
Adobe Patches for February 2026
Zero-day Vulnerabilities Patched inFebruaryPatch Tuesday Edition
Critical Severity Vulnerabilities Patched inFebruaryPatch Tuesday Edition
Other Microsoft Vulnerability Highlights
Microsoft Release Summary
Discover and Prioritize Vulnerabilities inVulnerability Management, Detection & Response (VMDR)
Rapid Response with TruRisk Eliminate
Qualys Monthly Webinar Series
Microsoft’s February 2026 Patch Tuesday focuses on closing security gaps that attackers could exploit, reinforcing the importance of timely patching in enterprise environments. Here’s a quick breakdown of what you need to know.
## Microsoft Patch Tuesday for February 2026
This month’s release addresses 61 vulnerabilities, i
Bleepingcomputer
Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws
blogs_bleepingcomputer·2026-02-10·CVSS 8.8
[HIGH] Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws
## Microsoft February 2026 Patch Tuesday fixes 6 zero-days, 58 flaws
## Lawrence Abrams
25 Elevation of Privilege vulnerabilities
5 Security Feature Bypass vulnerabilities
12 Remote Code Execution vulnerabilities
6 Information Disclosure vulnerabilities
3 Denial of Service vulnerabilities
7 Spoofing vulnerabilities
When BleepingComputer reports on Patch Tuesday security updates, we only count those released by Microsoft today. Therefore, the number of flaws does not include 3 Microsoft Edge flaws fixed earlier this month.
As part of these updates, Microsoft has also begun to roll out updated Secure Boot certificates to replace the original 2011 certificates that are expiring in late June 2026.
"With this update, Windows quality updates include a broad set of targeting data that i
Qualys
Microsoft and Adobe Patch Tuesday, February 2026 Security Update Review | Qualys
blogs_qualys·2026-02-10
Microsoft and Adobe Patch Tuesday, February 2026 Security Update Review | Qualys
#### Table of Contents
- Microsoft Patch Tuesday forFebruary2026
- Adobe Patches for February 2026
- Zero-day Vulnerabilities Patched inFebruaryPatch Tuesday Edition
- Critical Severity Vulnerabilities Patched inFebruaryPatch Tuesday Edition
- Other Microsoft Vulnerability Highlights
- Microsoft Release Summary
- Discover and Prioritize Vulnerabilities inVulnerability Management, Detection & Response (VMDR)
- Rapid Response with TruRisk Eliminate
- Qualys Monthly Webinar Series
Microsoft’s February 2026 Patch Tuesday focuses on closing security gaps that attackers could exploit, reinforcing the importance of timely patching in enterprise environments. Here’s a quick breakdown of what you need to know.
## Microsoft Patch Tuesday for February 2026
This month’s release addresses 61 vulner
Zscaler
Zscaler protects against 9 new vulnerabilities | 02-10-2026
blogs_zscaler·CVSS 7.8
[HIGH] Zscaler protects against 9 new vulnerabilities | 02-10-2026
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Wiz
CVE-2026-21241 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.0
CVE-2026-21241 [HIGH] CVE-2026-21241 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-21241 :
vulnerability analysis and mitigation
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
Source : NVD
## 7
Score
Published February 10, 2026
Severity HIGH
CNA Score 7.0
Has Public Exploit No
Has CISA KEV Exploit No
CISA KEV Release Date N/A
CISA KEV Due Date N/A
Exploitation Probability Percentile (EPSS) 7.2
Exploitation Probability (EPSS) N/A
Sources
NVD
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Sophos
February’s Patch Tuesday assumes battle stations
blogs_sophos
February’s Patch Tuesday assumes battle stations
Share This
Microsoft on Tuesday released 58 patches affecting 15 product families. Five of the addressed issues, all involving Azure, are considered by Microsoft to be of Critical severity, though only two require urgent attention (more on that below). Fifteen have a CVSS base score of 8.0 or higher, including two with a 9.8 base score. Six are known to be under active exploit in the wild, and three are publicly disclosed (including one not yet known to be under exploit).
At patch time, five CVEs are judged more likely to be exploited in the next 30 days by the company’s estimation, in addition to the six already detected to be so. Various of this month’s issues are amenable to direct detection by Sophos protections, and we include information on those in a table below. The release also
2026-02-10
Published