CVE-2026-81391ImportantRevised 17 Sep
Microsoft Excel Information Disclosure Vulnerability
Assessment
Use of uninitialized resource in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
- Severity
- Important
- CVSS base score
- 5.5CVSS:3.1/
AV:L/ AC:L/ PR:N/ UI:R/ S:U/ C:H/ I:N/ A:N/ E:U/ RL:O/ RC:C - Impact
- Information Disclosure
- EPSS, next 30 days
- 0.5%Higher than 43.2% of scored CVEs · FIRST model run 26 Sep 2026 · about EPSS
- Exploitability
- Exploitation Less Likely
- Publicly disclosed
- No
- Customer action
- Required: apply the update
- Component
- Microsoft Office Excel
- Weakness
- CWE-908: Use of Uninitialized Resource
- Issued by
- Microsoft
- Published
- 8 Sep 2026 · September 2026
- Last revised
- 17 Sep 2026Microsoft is announcing the availability of the security updates for Microsoft Office for Mac. Customers running affected Mac software should install the update for their product to be protected from this vulnerability. Customers running other Microsoft Office software do not need to take any actio…
Updates that fix it
2 KBs| KB | Type | Restart | Applies to | Other CVEs |
|---|---|---|---|---|
| KB5002904 | Security Update | — | Microsoft Office 2016 (32-bit edition), Microsoft Office 2016 (64-bit edition) | All CVEs in KB5002904 |
| KB5002914 | Security Update | — | Microsoft Excel 2016 (32-bit edition), Microsoft Excel 2016 (64-bit edition) | All CVEs in KB5002914 |
Affected products
Microsoft Office15 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 2016 (32-bit edition)
- Microsoft Office 2016 (64-bit edition)
- Microsoft Office 2019 for 32-bit editions
- Microsoft Office 2019 for 64-bit editions
- Microsoft Office 365 for Mac
- 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