Buffer overflow in Microsoft 365_apps
CVE-2026-40364
Access of resource using incompatible type ('type confusion') in Microsoft Office Word allows an unauthorized attacker to execute code locally.
Vulnerability class: Buffer Overflow
EPSS: 0.002 (40.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.4 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Microsoft 365_apps
- Microsoft 365 Apps For Enterprise — versions 16.0.1
- Microsoft Office 2019 — versions 19.0.0
- Microsoft Office Ltsc 2021 — versions 16.0.1
- Microsoft Office Ltsc 2024 — versions 16.0.0
- Microsoft Office Ltsc For Mac 2021 — versions 16.0.1
- Microsoft Office Ltsc For Mac 2024 — versions 16.0.0
- Microsoft Word 2016 — versions 16.0.1
- Microsoft Office — versions 2019
- Microsoft Office_long_term_servicing_channel — versions 2021, 2024
Weakness classification (CWE)
References
- Microsoft Word Remote Code Execution Vulnerability (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-40364?
- CVE-2026-40364 is a high-severity vulnerability in Microsoft 365_apps, classified under Heap-based Buffer Overflow. CVSS score: 8.4/10. Published 2026-05-12.
- How severe is CVE-2026-40364?
- High severity. CVSS v3 base score is 8.4 out of 10.