Microsoft Word Remote Code Execution Vulnerability
CVE-2026-40366 is a critical use-after-free vulnerability in Microsoft Office Word. Microsoft classifies it as a Remote Code Execution vulnerability and maps it to CWE-416. The flaw arises from improper handling of object lifetime in Word, leading to a use-after-free condition that can be triggered during document processing. Microsoft states that the Preview Pane is an attack vector for this issue, meaning exploitation may occur when a specially crafted Word document is previewed rather than fully opened. Although the CVE title uses 'Remote Code Execution,' the published Microsoft description states that an unauthorized attacker can execute code locally.
Are you exposed to this one?
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
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.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
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.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
5 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Microsoft Word remote code execution vulnerability that can be exploited via the Preview Pane.
A Microsoft Word remote code execution vulnerability that can be exploited via the Preview Pane.
A critical use-after-free vulnerability in Microsoft Word that allows local code execution.
A critical use-after-free remote code execution vulnerability in Microsoft Office Word that allows an unauthorized attacker to execute code locally, including via the Preview Pane attack vector.
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.