CVE-2026-64911 Microsoft CVE debrief

Who should care

Defenders and administrators responsible for Microsoft Office installations should assess exposure and apply the patch to prevent potential attacks. They should also inventory and monitor Microsoft Office installations for potential vulnerability and assess and mitigate risks associated with unauthorized code execution.

Why it matters

The vulnerability allows an unauthorized attacker to execute code locally, posing a significant risk to Microsoft Office installations. Defenders and administrators should assess exposure and apply the patch.

• Verify and apply patches for Microsoft Office to prevent local code execution
• Inventory and monitor Microsoft Office installations for potential vulnerability
• Assess and mitigate risks associated with unauthorized code execution

Technical summary

The vulnerability is caused by an integer overflow or wraparound in Microsoft Office, allowing an unauthorized attacker to execute code locally. This vulnerability affects Microsoft Office installations and poses a significant risk to defenders and administrators. The vulnerability can be exploited by an unauthorized attacker to execute malicious code, making it essential for defenders and administrators to assess exposure and apply the patch.

Defensive priority

High

Recommended defensive actions

• Review and apply the Microsoft patch for the vulnerability
• Inventory Microsoft Office installations to identify potentially affected systems
• Monitor for suspicious activity related to the vulnerability

Evidence notes

The CVE record and NVD vulnerability detail provide information on the vulnerability. Microsoft has released a patch for the vulnerability. The vulnerability allows an unauthorized attacker to execute code locally, posing a significant risk to Microsoft Office installations. Defenders and administrators should assess exposure and apply the patch. The CVE record was published on 2026-08-11T17:06:42.620Z and has not been modified since then. There is no information on known or unknown R

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.