4.3

CVE-2026-40421: microsoft 365_apps External Control of File Name or Path

CVSS: 4.3v3.1MediumModified
Published 12-05-2026Last modified 10-08-2026
Open JSON

Vulnerability summary

CVE-2026-40421 is a medium (CVSS 4.3) External Control of File Name or Path vulnerability in microsoft 365_apps. EPSS estimates a 0.70% chance of exploitation in the next 30 days, higher than 52.5% of scored vulnerabilities.

Overall risk
17/100
0100
Low · default modelHow is this calculated?
CVSS score
4.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.70%
0%100%
Low · +0.08 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 12-05-2026
    PublishedVulnerability first disclosed.
  2. 10-08-2026
    Last modifiedVulnerability information updated.

Description

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

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.70%

Chance of exploitation in the next 30 days

Percentile

53%

Versus all other CVEs

30-day change

+0.08 pp

From 0.62% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.70%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Microsoft9 products

1 vendor · 9 products

References

1 links