CVE-2026-21242
published 2026-02-10CVE-2026-21242: Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.
PriorityP338high7CVSS 3.1
AVLACHPRLUINSUCHIHAH
EPSS
0.34%
26.2th percentile
Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.
Affected
32 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| microsoft | windows_10_21h2 | < 10.0.19044.6937 | 10.0.19044.6937 |
| microsoft | windows_10_22h2 | < 10.0.19045.6937 | 10.0.19045.6937 |
| microsoft | windows_10_version_21h2 | >= 10.0.19044.0 < 10.0.19044.6937 | 10.0.19044.6937 |
| microsoft | windows_10_version_22h2 | >= 10.0.19045.0 < 10.0.19045.6937 | 10.0.19045.6937 |
| 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_10_version_21h2_for_arm64-based_systems | — | — |
| msrc | windows_10_version_21h2_for_x64-based_systems | — | — |
| msrc | windows_10_version_22h2_for_arm64-based_systems | — | — |
| msrc | windows_10_version_22h2_for_x64-based_systems | — | — |
| 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 | — | — |
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-5w28-wvm6-xf4j: Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally
ghsa_unreviewed·2026-02-10
CVE-2026-21242 [HIGH] CWE-416 GHSA-5w28-wvm6-xf4j: Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally
Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.
Microsoft
Windows Subsystem for Linux Elevation of Privilege Vulnerability
vendor_msrc·2026-02-10·CVSS 7.0
CVE-2026-21242 [HIGH] CWE-416 Windows Subsystem for Linux Elevation of Privilege Vulnerability
Windows Subsystem for Linux Elevation of Privilege Vulnerability
Description: Use after free in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.
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.
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.
Windows Subsystem for Linux: Windows Subsystem for Linux
Microsoft: Microsoft
Customer Action Required: Yes
Impact: Elevation
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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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
Wiz
CVE-2026-21242 Impact, Exploitability, and Mitigation Steps | Wiz
blogs_wiz·CVSS 7.0
CVE-2026-21242 [HIGH] CVE-2026-21242 Impact, Exploitability, and Mitigation Steps | Wiz
## CVE-2026-21242 :
vulnerability analysis and mitigation
Use after free in Windows Subsystem for Linux 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) 10.5
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
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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