What is CVE-2026-78502?

CVE-2026-78502 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-09-08.

How severe is CVE-2026-78502?

Medium severity. CVSS v3 base score is 6.5 out of 10.

Out-of-bounds Read in Microsoft 365 Apps

CVE-2026-78502

Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information over a network.

Vulnerability class: Buffer Overflow

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.

Affected products

Microsoft 365_apps
Microsoft Microsoft_365
Microsoft 365 Apps For Enterprise
Microsoft Office 2019
Microsoft Office 365 For Mac
Microsoft Office Ltsc 2021
Microsoft Office Ltsc 2024
Microsoft Office Ltsc For Mac 2021
Microsoft Office Ltsc For Mac 2024
Microsoft Word 2016

Weakness classification (CWE)

CWE-125 — Out-of-bounds Read

References

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

Frequently asked questions

What is CVE-2026-78502?: CVE-2026-78502 is a medium-severity vulnerability in Microsoft 365 Apps, classified under Out-of-bounds Read. CVSS score: 6.5/10. Published 2026-09-08.
How severe is CVE-2026-78502?: Medium severity. CVSS v3 base score is 6.5 out of 10.