CVE-2026-40363
High
Description
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
SeverityHigh
CVSS8.4
Exploit probability—
Product
Microsoft Office
PublishedMay 12, 2026
First seenMay 12, 2026
Weakness typeCWE-122CWE-122
How to fix
Update
- microsoft 365_copilot16.0.19822.20190 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| microsoft office | 2016, 2019 | — |
| microsoft 365_apps | No range specified | — |
| microsoft 365_copilot | v < 16.0.19822.20190 | 16.0.19822.20190 |
| microsoft office_long_term_servicing_channel | 2021, 2024 | — |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
In the Intelligence 360 plan
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.