What’s Vulnerable › Vulnerabilities

CVE-2024-21413: Microsoft Outlook Remote Code Execution Vulnerability

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: yes — in CISA KEV since 2025-02-06
• EPSS: 94.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2024-02-13 · updated 2026-08-10
• Weakness: CWE-20

Description

Microsoft Outlook Remote Code Execution Vulnerability

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Office 2016: all versions
• Microsoft Office 2019: all versions
• 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 LTSC 2021: from 16.0.1 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Office: from 16.0.0 before 16.0.5435.1001 — fixed in 16.0.5435.1001

How to fix

Upgrade to a fixed version: Microsoft 365 Apps https://aka.ms/OfficeSecurityReleases; Microsoft Office LTSC 2021 https://aka.ms/OfficeSecurityReleases; Microsoft Office 16.0.5435.1001. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413
• https://research.checkpoint.com/2024/the-risks-of-the-monikerlink-bug-in-microsoft-outlook-and-the-big-picture/
• https://www.vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-detection-script
• https://www.vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-mitigation-script
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21413

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