CVE-2026-40364Critical
Microsoft Word Remote Code Execution Vulnerability
Assessment
Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
- Severity
- Critical
- CVSS base score
- 8.4CVSS:3.1/
AV:L/ AC:L/ PR:N/ UI:N/ S:U/ C:H/ I:H/ A:H/ E:U/ RL:O/ RC:C - Impact
- Remote Code Execution
- EPSS, next 30 days
- 0.4%Higher than 27.7% of scored CVEs · FIRST model run 29 Sep 2026 · about EPSS
- Public exploit code
- No Nuclei template lists it
- Exploitability
- Exploitation More Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Microsoft Office Word
- Weakness
- CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')
- Issued by
- Microsoft
- Published
- 12 May 2026 · May 2026
- Last revised
- 12 May 2026
Updates that fix it
1 KB| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5002858 | Security Update | — | Microsoft Word 2016 (32-bit edition), Microsoft Word 2016 (64-bit edition) | All CVEs in KB5002858 |
Affected products
Microsoft Office12 affected products
- Microsoft 365 Apps for Enterprise for 32-bit Systems
- Microsoft 365 Apps for Enterprise for 64-bit Systems
- Microsoft Office 2019 for 32-bit editions
- Microsoft Office 2019 for 64-bit editions
- Microsoft Office LTSC 2021 for 32-bit editions
- Microsoft Office LTSC 2021 for 64-bit editions
- Microsoft Office LTSC 2024 for 32-bit editions
- Microsoft Office LTSC 2024 for 64-bit editions
- Microsoft Office LTSC for Mac 2021
- Microsoft Office LTSC for Mac 2024
- Microsoft Word 2016 (32-bit edition)
- Microsoft Word 2016 (64-bit edition)