What’s Vulnerable › Vulnerabilities

CVE-2020-16957: Microsoft Office Access Connectivity Engine Remote Code Execution Vulnerability

• Severity: critical (CVSS 9.3 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-10-16 · updated 2026-06-17

Description

<p>A remote code execution vulnerability exists when the Microsoft Office Access Connectivity Engine improperly handles objects in memory. An attacker who successfully exploited this vulnerability could execute arbitrary code on a victim system.</p> <p>An attacker could exploit this vulnerability by enticing a victim to open a specially crafted file.</p> <p>The update addresses the vulnerability by correcting the way the Microsoft Office Access Connectivity Engine handles objects in memory.</p>

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Office: 2019
• Microsoft 365 Apps: 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

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office https://aka.ms/OfficeSecurityReleases. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16957
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16957

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