Heap-based buffer overflow in Microsoft products - CVE-2026-50678
Published: July 17, 2026
Vulnerability identifier: #VU138179
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-50678
CWE-ID: CWE-122
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to disclose sensitive information.
The vulnerability exists due to heap-based buffer overflow in Microsoft Office Excel when parsing a specially crafted file. A remote attacker can trick the victim into opening a crafted file to disclose sensitive information.
The Preview Pane is not an attack vector. An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.
Affected software
Microsoft Office for macOS
Microsoft Excel
Office Online Server
Microsoft Excel
Office Online Server
How to mitigate CVE-2026-50678
Install security update from vendor's website.
Microsoft Office for macOS - update to 16.111.26071215
Microsoft Excel - update to 16.0.5561.1001
Office Online Server - update to 16.0.10417.20175
Microsoft Excel - update to 16.0.5561.1001
Office Online Server - update to 16.0.10417.20175