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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.007 (51.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 51.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
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
- Microsoft Word Information Disclosure Vulnerability (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.