CVE-2024-21413
CriticalExploitedPublic exploitMicrosoft Outlook Remote Code Execution Vulnerability
Published Feb 16, 2024 · Updated Aug 10, 2026
Key Facts
Patch immediately- CVE-2024-21413 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting 365 Apps (Microsoft), Office 2016 (Microsoft), Office 2019 (Microsoft) and 3 more products.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 14, 2024. Public exploit code is available.
- EPSS estimates a 95% probability of exploitation in the next 30 days.
- Fixed versions are available, including Microsoft 365 Apps for Enterprise https://aka.ms/OfficeSecurityReleases, Office 2016 16.0.5435.1001, Office 2019 https://aka.ms/OfficeSecurityReleases.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
95%
Higher than 99.8% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2024-21413 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
Microsoft Outlook Remote Code Execution Vulnerability
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Feb 6, 2025 | Feb 27, 2025 | Not reported |
| Industry KEV feed | May 14, 2024 | Feb 27, 2025 | Not reported |
| CIRCL KEV | Feb 6, 2025 | Feb 27, 2025 | Not reported |
| ENISA EUVD | Feb 6, 2025 | n/a | Not reported |
Required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Affected Products
10 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| 365 AppsMicrosoft | See advisory | n/a |
| Office 2016Microsoft | >= 16.0.0 | 16.0.5435.1001 |
| Office 2019Microsoft | >= 19.0.0 | https://aka.ms/OfficeSecurityReleases |
| Office Long Term Servicing ChannelMicrosoft | 2021 | n/a |
| Microsoft 365 Apps for Enterprise | >= 16.0.1 | https://aka.ms/OfficeSecurityReleases |
Patched Releases
Microsoft 365 Apps for Enterprise
https://aka.ms/OfficeSecurityReleases
Office 2016
16.0.5435.1001
Office 2019
https://aka.ms/OfficeSecurityReleases
Microsoft Office LTSC 2021
https://aka.ms/OfficeSecurityReleases
Timeline
Publicly disclosed
Feb 16, 2024
Added to Industry KEV feed
May 14, 2024
Added to CISA KEV
Feb 6, 2025
Added to CIRCL KEV
Feb 6, 2025
Added to ENISA EUVD
Feb 6, 2025
Last updated
Aug 10, 2026
Weakness Type
- CWE-20 Improper Input Validation
References
- advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-20673
- advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-20684
- advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21315
- advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21327
- advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21338
FAQ
Common Questions.
Microsoft Outlook Remote Code Execution Vulnerability
Affected: 365 Apps (Microsoft); Office 2016 (Microsoft) versions >= 16.0.0; Office 2019 (Microsoft) versions >= 19.0.0, among others. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since May 14, 2024.
Yes. It was added on Feb 6, 2025 with a federal remediation due date of Feb 27, 2025.
Public exploit code is available.
Fixed versions are available, including Microsoft 365 Apps for Enterprise https://aka.ms/OfficeSecurityReleases, Office 2016 16.0.5435.1001, Office 2019 https://aka.ms/OfficeSecurityReleases.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2024-21413 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo