Summary
Impact: Information Disclosure. Microsoft rating: Important. Not known to be exploited — Exploitation Unlikely. Customer action: Required.
Details
What type of information could be disclosed by this vulnerability?
An attacker who successfully exploited this vulnerability could potentially read small portions of heap memory.
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.
Is the Preview Pane an attack vector for this vulnerability?
No, the Preview Pane is not an attack vector.
Security updates
16.0.10417.20128 — https://support.microsoft.com/help/5002871
https — https://docs.microsoft.com/en-us/officeupdates/microsoft365-apps-security-updates
16.109.26051019 — https://go.microsoft.com/fwlink/p/?linkid=831049
16.0.5552.1000 — https://support.microsoft.com/help/5002865
Vulnerabilities 1
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High 7.8
Microsoft Excel Information Disclosure Vulnerability
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information locally.
Revision history
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#1
Information published.
References
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CVE-2026-40360 Microsoft Excel Information Disclosure Vulnerability - HTML
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40360
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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