CVE-2026-78518

Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.

Score

CVSS 3.1 8.8 High

Status

Analyzed - secure@microsoft.com

Published

2026-09-08

Last modified

2026-10-14

Weaknesses

CWE-125, CWE-20

Affected products

• 365 Apps (Microsoft)
• Excel (Microsoft)
• Excel 2016 (Microsoft)
• Microsoft 365 (Microsoft)
• Office 2016 (Microsoft)
• Office 2019 (Microsoft)
• Office 2021 (Microsoft)
• Office 2024 (Microsoft)
• Office 365 (Microsoft)
• Office Macos 2021 (Microsoft)
• Office Macos 2024 (Microsoft)

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-78518