Critical 9.8Known exploited (CISA KEV)Published Feb 13, 2024

CVE-2024-21413Microsoft Outlook Remote Code Execution Vulnerability

Updated under an hour ago (Oct 27, 2026, 9:50 PM ET)

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It affects Microsoft 365 Apps for Enterprise and 5 other products. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Feb 6, 2025; federal agencies had to remediate by Feb 27, 2025. Treat that date as your deadline.

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Exploited in the last 30 days

Microsoft Outlook Remote Code Execution Vulnerability

CVSS: 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Weakness (CWE): CWE-20
Known exploited: Added to CISA KEV Feb 6, 2025; federal remediation due Feb 27, 2025Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
EPSS (exploitation in the next 30 days): 94.66% (percentile 100)
Assigned by: microsoft
NVD analysis: Analyzed
Record last updated: Aug 10, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Microsoft Microsoft 365 Apps for Enterprise microsoft:365_apps_for_enterprise (from the name)	from 16.0.1 before https://aka.ms/OfficeSecurityReleases	CNA record
Microsoft Microsoft Office 2016 microsoft:office_2016 (from the name)	from 16.0.0 before 16.0.5435.1001	CNA record
Microsoft Microsoft Office 2019 microsoft:office_2019 (from the name)	from 19.0.0 before https://aka.ms/OfficeSecurityReleases	CNA record
Microsoft Microsoft Office LTSC 2021 microsoft:office_ltsc_2021 (from the name)	from 16.0.1 before https://aka.ms/OfficeSecurityReleases	CNA record
microsoft 365_apps microsoft:365_apps	all versions	NVD
microsoft office_2016 microsoft:office_2016	all versions; all versions	NVD
microsoft office_2019 microsoft:office_2019	all versions; all versions	NVD
microsoft office_long_term_servicing_channel microsoft:office_long_term_servicing_channel	2021	NVD

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.