Summary
Impact: Remote Code Execution. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
How could an attacker exploit this vulnerability?
An attacker could send a specially crafted Excel workbook and convince a user to open it for editing and begin typing a formula. Successful exploitation could allow the attacker to execute code with the permissions of the user running Excel. The attacker does not need an account on the affected system.
Security updates
16.0.14334.21048 — https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
https — https://learn.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
16.115.26110837 — https://learn.microsoft.com/en-us/officeupdates/release-notes-office-for-mac
16.0.10417.20236 — https://support.microsoft.com/help/5002946
Vulnerabilities 1
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High 8.8
Microsoft Office Excel Remote Code Execution Vulnerability
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code over a network.
Revision history
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#1
Information published.
References
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CVE-2026-118721 Microsoft Office Excel Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-118721
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Microsoft Exploitability Index
https://www.microsoft.com/en-us/msrc/exploitability-index?rtc=1
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Microsoft Support Lifecycle
https://support.microsoft.com/lifecycle
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Common Vulnerability Scoring System
https://www.first.org/cvss