Out-of-bounds read in Microsoft products - CVE-2026-78518
Published: September 9, 2026
Vulnerability identifier: #VU148236
CSH Severity: High
CVSS v4: 8.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-78518
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to execute arbitrary code.
The vulnerability exists due to an out-of-bounds read in Microsoft Office Excel when opening a specially crafted Office file. A remote attacker can send a malicious Office file and convince a user to open it to execute arbitrary code.
The Preview Pane is not an attack vector.
Affected software
Microsoft Excel
Microsoft 365 Apps for Enterprise
Microsoft Office
Microsoft 365 Apps for Enterprise
Microsoft Office
How to mitigate CVE-2026-78518
Install security update from vendor's website.
Microsoft Excel - update to 16.0.5569.1003
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1003, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976
Microsoft 365 Apps for Enterprise - update to 16.0.20326.20138
Microsoft Office - addressed in versions 16.0.5569.1003, 16.0.10417.20207, 16.0.14334.20906, 16.0.17932.20976