What’s Vulnerable › Vulnerabilities

CVE-2024-21378: Microsoft Outlook Remote Code Execution Vulnerability

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 11.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-02-13 · updated 2026-08-10
• Weakness: CWE-94

Description

Microsoft Outlook Remote Code Execution Vulnerability

Affected products

• Microsoft 365 Apps: all versions
• Microsoft Office: 2019
• Microsoft Office LTSC for Mac 2021: 2021
• Microsoft Outlook: 2016
• 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 19.0.0 before https://aka.ms/OfficeSecurityReleases — fixed in https://aka.ms/OfficeSecurityReleases
• Microsoft Outlook 2016 for Mac: from 16.0.0.0 before 16.0.5435.1000 — fixed in 16.0.5435.1000

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 https://aka.ms/OfficeSecurityReleases; Microsoft Outlook 2016 for Mac 16.0.5435.1000. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21378
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21378

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