CVE-2023-36766: Microsoft Excel Information Disclosure Vulnerability

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-09-12 · updated 2026-06-17
Weakness: CWE-125

Description

Microsoft Excel Information Disclosure Vulnerability

Affected products

Microsoft 365 Apps: all versions
Microsoft Excel 2013 Service Pack 1: 2013-sp1, 2016
Microsoft Office: 2019
Microsoft Office LTSC for Mac 2021: 2021
Microsoft Office Online Server: all versions
Microsoft 365 Apps: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Excel 2013 Service Pack 1: from 15.0.0.0 before 15.0.5589.1000 — fixed in 15.0.5589.1000
Microsoft Excel 2016: from 16.0.0.0 before 16.0.5413.1000 — fixed in 16.0.5413.1000
Microsoft Office 2019 for Mac: from 16.0.0 before 16.77.23091003 — fixed in 16.77.23091003
Microsoft Office LTSC 2021: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Office: from 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC for Mac 2021: from 16.0.1 before 16.77.23091003 — fixed in 16.77.23091003
Microsoft Office Online Server: from 16.0.1 before 16.0.10402.20000 — fixed in 16.0.10402.20000

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Excel 2013 Service Pack 1 15.0.5589.1000; Microsoft Excel 2016 16.0.5413.1000; Microsoft Office 2019 for Mac 16.77.23091003; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC for Mac 2021 16.77.23091003; Microsoft Office Online Server 16.0.10402.20000. Check the vendor advisory for mitigations.

References

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