Vulnerability in Microsoft 365_apps
CVE-2026-40421
Files or directories accessible to external parties in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
EPSS: 0.001 (16.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N.
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 Word 2016 — versions 16.0.1
- Microsoft Office — versions 2019, 2021, 2024
- Microsoft Office_long_term_servicing_channel — versions 2021
- Microsoft Word — versions 2016
Weakness classification (CWE)
References
- secure@microsoft.com (vendor-advisory, patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-40421?
- CVE-2026-40421 is a medium-severity vulnerability in Microsoft 365_apps, classified under External Control of File Name or Path. CVSS score: 4.3/10. Published 2026-05-12.
- How severe is CVE-2026-40421?
- Medium severity. CVSS v3 base score is 4.3 out of 10.