CVE-2026-40359Important
Microsoft Excel Remote Code Execution Vulnerability
Assessment
Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
- Severity
- Important
- CVSS base score
- 7.8CVSS:3.1/
AV:L/ AC:L/ PR:N/ UI:R/ S:U/ C:H/ I:H/ A:H/ E:U/ RL:O/ RC:C - Impact
- Remote Code Execution
- EPSS, next 30 days
- 0.5%Higher than 37.9% of scored CVEs · FIRST model run 29 Sep 2026 · about EPSS
- Public exploit code
- No Nuclei template lists it
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Microsoft Office Excel
- Weakness
- CWE-416: Use After Free
- Issued by
- Microsoft
- Published
- 12 May 2026 · May 2026
- Last revised
- 12 May 2026
Updates that fix it
2 KBs| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5002865 | Security Update | — | Microsoft Excel 2016 (32-bit edition), Microsoft Excel 2016 (64-bit edition) | All CVEs in KB5002865 |
| KB5002871 | Security Update | — | Office Online Server | All CVEs in KB5002871 |
Affected products
Microsoft Office13 affected products
- Microsoft 365 Apps for Enterprise for 32-bit Systems
- Microsoft 365 Apps for Enterprise for 64-bit Systems
- Microsoft Excel 2016 (32-bit edition)
- Microsoft Excel 2016 (64-bit edition)
- 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
- Office Online Server