CVE-2024-21413
Microsoft Outlook Improper Input Validation Vulnerability
Microsoft Office OutlookApplications & CMS
CVSS
9.8CriticalExploit odds (EPSS)94.7%Chance of exploitation activity in the next 30 days, higher than 99% of CVEs. Scored 23 Oct 2026FIRST EPSS
CISA required actionApply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. CISA KEV
What fixes it
- 16.0.5435.1001Microsoft Office 2016CVE List
A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.
Timeline
Description
Microsoft Outlook contains an improper input validation vulnerability that allows for remote code execution. Successful exploitation of this vulnerability would allow an attacker to bypass the Office Protected View and open in editing mode rather than protected mode.
Text from CVE List
Affected versions 4
- Microsoft 365 Apps for Enterpriseaffected: 16.0.1 before https://aka.ms/OfficeSecurityReleasesCVE List
- Microsoft Office 2016affected: 16.0.0 before 16.0.5435.1001CVE List
- Microsoft Office 2019affected: 19.0.0 before https://aka.ms/OfficeSecurityReleasesCVE List
- Microsoft Office LTSC 2021affected: 16.0.1 before https://aka.ms/OfficeSecurityReleasesCVE List
References 6
- msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413Advisoryvia CVE List
- nvd.nist.gov/vuln/detail/CVE-2024-21413Referencevia CISA KEV
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21413Referencevia CVE List
- vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-mitigation-scriptReferencevia CVE List
- vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-detection-scriptReferencevia CVE List
- research.checkpoint.com/2024/the-risks-of-the-monikerlink-bug-in-microsoft-outlook-and-the-big-picture/Referencevia CVE List