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High

RCE in Windows Win32K-GRFX via Integer Overflow or Wraparound

IdentifiersCVE-2026-44803CWE-190· Integer Overflow or Wraparound

CVE-2026-44803 is a critical remote code execution vulnerability in the Windows Graphics Component, specifically Windows Win32K-GRFX. The flaw is caused by an integer overflow or wraparound condition. Microsoft states that successful exploitation allows an unauthorized attacker to execute code locally. Available reporting indicates the vulnerable path can be triggered through processing of a specially crafted file, including when the file is viewed in the Windows File Explorer Preview Pane or opened directly. Although categorized as remote code execution, the CVSS vector is local with user interaction required (AV:L/AC:L/PR:N/UI:R), reflecting that attacker-controlled content must be rendered or parsed on the target system rather than exploited over the network directly.

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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 result in arbitrary code execution on the target Windows system. Microsoft rates confidentiality, integrity, and availability impact as High, indicating the attacker may be able to run malicious code that can access data, modify system or user content, and disrupt system operation. Reporting around the June 2026 Patch Tuesday cycle describes the issue as potentially enabling compromise from a single preview or open action on a malicious file.

Mitigation

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

Until patches are fully deployed, reduce exposure by preventing users from opening or previewing untrusted files, especially in Windows File Explorer Preview Pane. Limit delivery of attacker-controlled files through email, downloads, and shared content channels where possible. Where operationally feasible, disable or avoid use of preview functionality for untrusted content and apply standard content-handling controls such as attachment filtering and user awareness for suspicious files.

Remediation

Patch, then assume compromise.

Install Microsoft's security update for CVE-2026-44803 on affected Windows systems. Microsoft also noted that, at initial publication, updates for Microsoft Word for Android, Microsoft PowerPoint for Android, and Microsoft Excel for Android were not yet available and would be released later via a revision to the CVE information. Ensure all relevant platform and application updates associated with this CVE are applied once available.
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 CorporationExcelapplication
Microsoft CorporationPowerpointapplication
Microsoft CorporationWindowsoperating_system
Microsoft CorporationWindows 10 1607operating_system
Microsoft CorporationWindows 10 1809operating_system
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 2012operating_system
Microsoft CorporationWindows Server 2012 R2operating_system
Microsoft CorporationWindows Server 2016operating_system
Microsoft CorporationWindows Server 2019operating_system
Microsoft CorporationWindows Server 2022operating_system
Microsoft CorporationWindows Server 2025operating_system
Microsoft CorporationWordapplication

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

What this page doesn’t show

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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

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