Summary
Impact: Information Disclosure. Microsoft rating: Important. Not known to be exploited — Exploitation Less Likely. Customer action: Required.
Details
What type of information could be disclosed by this vulnerability?
An attacker who successfully exploited this vulnerability could potentially read portions of process memory.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
Security updates
https — https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
16.112.26081010 — https://go.microsoft.com/fwlink/p/?linkid=831049
16.0.5565.1000 — https://support.microsoft.com/help/5002901
16.112.26081010 — https://www.microsoft.com/en-us/microsoft-365/mac/microsoft-365-for-mac?msockid=35f9adb0e74b61392038b90de6fe608c
Vulnerabilities 1
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Medium 5.5
Microsoft Office Graphics Component Information Disclosure Vulnerability
Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally.
Revision history
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#2
Updated an acknowledgement. This is an informational change only.
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#1
Information published.
References
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CVE-2026-66809 Microsoft Office Graphics Component Information Disclosure Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66809
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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