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Win32k Elevation of Privilege Vulnerability in Windows Win32K - ICOMP

IdentifiersCVE-2026-33840CWE-416· Use After Free

CVE-2026-33840 is a Microsoft Windows Win32k elevation-of-privilege vulnerability affecting the Win32K - ICOMP component. The flaw is a use-after-free condition (CWE-416) in which memory is accessed after it has been freed, creating a condition that can be leveraged by a local attacker with low privileges to corrupt kernel memory and elevate execution context. Microsoft classifies the issue as Important and indicates that successful exploitation can result in SYSTEM-level privileges. The available information identifies the affected area as Win32K - ICOMP, but does not provide function-level or code-path specifics.

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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 local authorized attacker to elevate privileges from a low-privileged context to SYSTEM. Given the CVSS vector and Microsoft’s assessment, the resulting impact includes high confidentiality, integrity, and availability impact on the affected system, enabling full compromise of the local host.

Mitigation

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

No specific vendor mitigation beyond patching is provided in the supplied content. As temporary risk reduction, limit local access to trusted users, minimize the number of low-privileged accounts on affected systems, enforce least privilege, and monitor for suspicious local privilege-escalation activity until patches are fully deployed.

Remediation

Patch, then assume compromise.

Apply Microsoft's official security update for CVE-2026-33840 released as part of the May 12, 2026 security updates. Microsoft lists the remediation level as Official Fix. Organizations should deploy the relevant Windows patches to all affected systems and verify installation through normal patch validation processes.
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 CorporationWindowsoperating_system
Microsoft CorporationWindows 11 24h2operating_system
Microsoft CorporationWindows 11 25h2operating_system
Microsoft CorporationWindows 11 26h1operating_system
Microsoft CorporationWindows Server 2025operating_system

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

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.
Exposure mapping

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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 activity12

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