PT-2026-58591 · Microsoft · 365 Apps For Enterprise+5

Published 2026-07-14 · Updated 2026-07-14 · CVE-2026-56156

NVD

CVSS v3.1

7.8

High

Base vector

AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.

Fix

Heap Based Buffer Overflow

Weakness Enumeration

CWE-122

Related Identifiers

CVE-2026-56156

Affected Products

365 Apps For Enterprise

Office 365 For Mac

Office Ltsc 2021

Office Ltsc 2024

Office Ltsc For Mac 2021

Office Ltsc For Mac 2024

References · 2

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56156 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-56156 · Security Note