Microsoft Word Preview Pane Type Confusion RCE
CVE-2026-40364 is a Microsoft Office Word remote code execution vulnerability caused by access of a resource using an incompatible type (type confusion). The flaw affects Microsoft Word and is described in the provided content as a critical Word RCE with a CVSS score of 8.4. Multiple sources in the content state that exploitation can be triggered by a specially crafted malicious Word document and that the Preview Pane is a viable attack vector, meaning the target may not need to explicitly open the document for the vulnerable code path to be reached. The content also notes related weakness classes in Microsoft advisory material, including heap-based buffer overflow, but the primary weakness explicitly identified for this CVE is type confusion.
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Impact, mitigation & remediation
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Impact
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Mitigation
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Remediation
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Recent activity
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A Microsoft Word remote code execution vulnerability caused by type confusion that can be triggered through the Preview Pane without opening the malicious document.
A type confusion vulnerability in Microsoft Word that can trigger remote code execution when a crafted document is opened or previewed.
A critical Microsoft Word remote code execution vulnerability that can be triggered through the Preview Pane without opening the document, making user interaction requirements minimal.
A Microsoft Word remote code execution vulnerability exploitable via the Preview Pane and assessed by Microsoft as more likely to be exploited within 30 days.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.