What’s Vulnerable › Vulnerabilities

CVE-2021-43255: Microsoft Office Trust Center Spoofing Vulnerability

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-12-15 · updated 2026-06-17

Description

Microsoft Office Trust Center Spoofing Vulnerability

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Office: 2013-sp1, 2013_rt-sp1, 2016, 2019
• Microsoft Office LTSC for Mac 2021: 2021
• Microsoft 365 Apps: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office 2013 Service Pack 1: from 15.0.0 before 15.0.5407.1000 — fixed in 15.0.5407.1000
• 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

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office 2013 Service Pack 1 15.0.5407.1000; Microsoft Office LTSC 2021 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-2021-43255
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-43255

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