CVE-2026-40421 — Microsoft Word Information Disclosure Vulnerability

Executive Summary

Files or directories accessible to external parties in Microsoft Office Word allows an unauthorized attacker to disclose information locally.

Overview

4.3

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Information Disclosure

Released May 12 2026

Last Updated May 12 2026

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.0062 — 0.4494 percentile

NVD CVSS 4.3 MEDIUM — matches MSRC

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C

ATTACK VECTOR

Network

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

None

USER INTERACTION

Required

SCOPE

Unchanged

CONFIDENTIALITY

Low

INTEGRITY

None

AVAILABILITY

None

EXPLOIT CODE MATURITY

Unproven

REMEDIATION LEVEL

Official Fix

REPORT CONFIDENCE

Confirmed

Temporal Score: 3.8

EPSS Score

0.0062

probability of exploitation in the next 30 days

0.4494 percentile - updated 2026-06-21

View on FIRST.org

Affected Products

10 affected products

Product	KB Article	Severity	Impact	Restart Required
Microsoft 365 Apps for Enterprise for 32-bit Systems	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft 365 Apps for Enterprise for 64-bit Systems	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Office 2019 for 32-bit editions	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Office 2019 for 64-bit editions	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Office LTSC 2021 for 32-bit editions	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Office LTSC 2021 for 64-bit editions	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Office LTSC 2024 for 32-bit editions	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Office LTSC 2024 for 64-bit editions	`Click to Run (Security Update)`	Important	Information Disclosure	No
Microsoft Word 2016 (32-bit edition)	`5002858 (Security Update)`	Important	Information Disclosure	Maybe
Microsoft Word 2016 (64-bit edition)	`5002858 (Security Update)`	Important	Information Disclosure	Maybe

Patches

2 patches

Article	Type	Restart
`Click to Run`	Security Update	No
`5002858`	Security Update	Maybe

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

tiebuchen

References

MSRC Advisory MITRE NVD