# CVE-2026-40366: Microsoft Word Remote Code Execution Vulnerability

CVE-2026-40366 is fixed in 2 products on 1 platform, first by KB5002858, released May 12, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-40366
- Priority: Urgent
- CVSS: 8.4 (Critical)
- EPSS: 0.0038
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: May 12, 2026
- Weakness: Use After Free
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40366

## Description

<p>Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Word 2016 (32-bit edition) |  | [KB5002858](https://patchblox.com/security/data/fix/microsoft/kb5002858.md) | May 12, 2026 |
| Microsoft | Microsoft Word 2016 (64-bit edition) |  | [KB5002858](https://patchblox.com/security/data/fix/microsoft/kb5002858.md) | May 12, 2026 |

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Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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