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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 Windows Win32K - ICOMP. The flaw is a use-after-free condition (CWE-416) in the Win32k subsystem. Microsoft describes it as allowing an authorized attacker to elevate privileges locally. Based on the provided context, exploitation requires local access and low privileges, does not require user interaction, and can result in execution in a more privileged security context. No further public technical detail about the specific vulnerable routine or trigger path was provided in the supplied content.

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For your environment

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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 can elevate an attacker from a low-privileged local context to SYSTEM privileges. The supplied CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H) indicates high impact to confidentiality, integrity, and availability once exploited, consistent with full compromise of the affected host from a local foothold.

Mitigation

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

If immediate patching is not possible, reduce opportunities for local code execution by limiting interactive access to systems, minimizing assignment of local user privileges, restricting untrusted code execution through application control, and monitoring for suspicious post-compromise privilege-escalation behavior on Windows hosts. However, no vendor-specific workaround or mitigation beyond applying the official fix was provided in the supplied content.

Remediation

Patch, then assume compromise.

Apply Microsoft's official security update for CVE-2026-33840. Microsoft listed the remediation level as Official Fix and included the vulnerability in its May 12, 2026 security updates. The advisory was later updated on May 19, 2026 with an informational acknowledgement change only.
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 activity

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