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High

Windows Subsystem for Linux Race Condition Privilege Escalation

IdentifiersCVE-2026-21237CWE-362· Concurrent Execution using Shared…

CVE-2026-21237 is an elevation of privilege vulnerability in Windows Subsystem for Linux (WSL). The issue is described as concurrent execution using a shared resource with improper synchronization, i.e., a race condition, in WSL. An authorized attacker who already has local access to the affected Windows system can exploit this flaw to elevate privileges. No further public technical detail about the specific vulnerable function, code path, or exploitation sequence is provided in the supplied content.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a locally authorized attacker to elevate privileges on the affected system. This can enable execution with higher privileges than originally granted to the attacker, potentially facilitating full local compromise depending on the starting context and target environment.

Mitigation

If you can’t patch tonight, do this now.

If patching cannot be performed immediately, reduce exposure by limiting local access to trusted users only, restricting the ability to run or access WSL where operationally feasible, and monitoring for suspicious local privilege escalation activity involving WSL. These are interim risk-reduction measures only; the primary mitigation is vendor patching.

Remediation

Patch, then assume compromise.

Apply Microsoft's February 2026 security updates for affected Windows versions, including supported Windows 10 for x64-based Systems Version 21H2 and other affected supported product versions referenced by Microsoft. Microsoft has released patches for supported versions; installation should be verified via Windows Update, Update History, or the Microsoft Update Catalog if standalone packages are required.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft CorporationWindows 10 21h2operating_system
Microsoft CorporationWindows 10 22h2operating_system
Microsoft CorporationWindows 11 23h2operating_system
Microsoft CorporationWindows 11 24h2operating_system
Microsoft CorporationWindows 11 25h2operating_system
Microsoft CorporationWindows 11 26h1operating_system
Microsoft CorporationWindows Server 2022operating_system
Microsoft CorporationWindows Server 2022 23h2operating_system
Microsoft CorporationWindows Server 2025operating_system
Microsoft CorporationWindows Server 23h2operating_system
Microsoft CorporationWindows Subsystem For Linuxapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

7 SOURCESView more in app
What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-21237
NVD
nvd.nist.gov/vuln/detail/CVE-2026-21237
MITRE CWE · CWE-362
Concurrent Execution using Shared Resource…
Vendor Advisory
msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21237