What is CVE-2026-81387?

CVE-2026-81387 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Exposure of Sensitive System Information to an Unauthorized Control Sphere. CVSS score: 5.5/10. Published 2026-09-08.

How severe is CVE-2026-81387?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Vulnerability in Microsoft 365 Apps

CVE-2026-81387

Exposure of sensitive system information to an unauthorized control sphere in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

Affected products

Microsoft 365_apps
Microsoft Excel — versions 2016
Microsoft Microsoft_365
Microsoft 365 Apps For Enterprise
Microsoft Excel 2016
Microsoft Office 2016
Microsoft Office 2019
Microsoft Office 365 For Mac
Microsoft Office Ltsc 2021
Microsoft Office Ltsc 2024

Weakness classification (CWE)

CWE-497 — Exposure of Sensitive System Information to an Unauthorized Control Sphere

References

secure@microsoft.com (vendor-advisory, Patch, patch, Vendor Advisory)

Frequently asked questions

What is CVE-2026-81387?: CVE-2026-81387 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Exposure of Sensitive System Information to an Unauthorized Control Sphere. CVSS score: 5.5/10. Published 2026-09-08.
How severe is CVE-2026-81387?: Medium severity. CVSS v3 base score is 5.5 out of 10.