Summary
Impact: Remote Code Execution. Microsoft rating: Critical. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
According to the CVSS metric, the attack vector is local (AV:L). Why does the CVE title indicate that this is a remote code execution?
The word Remote in the title refers to the location of the attacker. This type of exploit is sometimes referred to as Arbitrary Code Execution (ACE). The attack itself is carried out locally. This means an attacker or victim needs to execute code from the local machine to exploit the vulnerability.
Is the Preview Pane an attack vector for this vulnerability?
Yes, the Preview Pane is an attack vector.
According to the CVSS metric, user interaction is required (UI:R). What interaction would the user have to do?
An attacker must send a user a malicious Office file and convince them to open it.
Security updates
16.112.26081010 — https://www.microsoft.com/en-us/microsoft-365/mac/microsoft-365-for-mac?msockid=35f9adb0e74b61392038b90de6fe608c
https — https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
16.112.26081010 — https://go.microsoft.com/fwlink/p/?linkid=831049
16.0.5565.1001 — https://support.microsoft.com/help/5002897
Vulnerabilities 1
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High 7.8
Microsoft Office Remote Code Execution Vulnerability
Integer underflow (wrap or wraparound) in Microsoft Office allows an unauthorized attacker to execute code locally.
Revision history
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#1
Information published.
References
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CVE-2026-64909 Microsoft Office Remote Code Execution Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64909
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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