CVE-2026-40421 | Microsoft Word Information Disclosure Vulnerability

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

Published: 2026-05-12 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-40421 is rated Low Risk (33.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.62%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-40421

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.05% 0.62% +0.57%
2 2026-05-18 0.05% 0.05% +0.01%
3 2026-05-13 — 0.05% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-40421

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]

Weakness enumeration for CVE-2026-40421

GitHub Security Advisory for CVE-2026-40421

GHSA-m493-43x7-h3mj · Severity: medium — External control of file name or path in Microsoft Office Word allows an unauthorized attacker to...

Affected software / configurations for CVE-2026-40421

Vendor Product Version Raw CPE
microsoft 365_apps — cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x64:*
microsoft 365_apps — cpe:2.3:a:microsoft:365_apps:-:*:*:*:enterprise:*:x86:*
microsoft office 2019 cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x64:*
microsoft office 2019 cpe:2.3:a:microsoft:office:2019:*:*:*:*:*:x86:*
microsoft office 2024 cpe:2.3:a:microsoft:office:2024:*:*:*:ltsc:*:x64:*
microsoft office 2024 cpe:2.3:a:microsoft:office:2024:*:*:*:ltsc:*:x86:*
microsoft office_long_term_servicing_channel 2021 cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:*:x64:*
microsoft office_long_term_servicing_channel 2021 cpe:2.3:a:microsoft:office_long_term_servicing_channel:2021:*:*:*:*:*:x86:*
microsoft word 2016 cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x64:*
microsoft word 2016 cpe:2.3:a:microsoft:word:2016:*:*:*:*:*:x86:*

References for CVE-2026-40421

cvelogic Threat Intelligence