CVEs / CVE-2024-21413
CVE-2024-21413: Microsoft Outlook Improper Input Validation Vulnerability
- Known exploited in the CISA KEV catalog since 6 Feb 2025
- critical 9.8 CVSS 3.1 (from the CNA)
- EPSS 94.6% chance of exploitation in the next 30 days, higher than 99% of CVEs (30 Oct 2026)
- Last changed at its sources
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Summary
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.
Description
Microsoft Outlook Remote Code Execution Vulnerability
Affected and fixed versions
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Microsoft 365 Apps for Enterprise | from 16.0.1, before https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft Microsoft Office 2016 | from 16.0.0, before 16.0.5435.1001 | 16.0.5435.1001 |
| Microsoft Microsoft Office 2019 | from 19.0.0, before https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
| Microsoft Microsoft Office LTSC 2021 | from 16.0.1, before https://aka.ms/OfficeSecurityReleases | https://aka.ms/OfficeSecurityReleases |
Exploitation
| In CISA KEV since | 6 Feb 2025 |
|---|---|
| Due date for US federal agencies | 27 Feb 2025 |
| Used in ransomware campaigns | Unknown |
| Required action | Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. |
Severity
| CVSS 3.1 | 9.8 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HScored by the CNA ([email protected]) |
|---|---|
| Weakness | CWE-20 |
References
- CVE-2024-21413 on NVD
- CVE-2024-21413 in the CISA KEV catalog
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413 (cited by CISA)
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413 Patch, Vendor Advisory
- 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
Sources
Exploitation status from the CISA Known Exploited Vulnerabilities catalog. EPSS scores from FIRST. Descriptions, severity and references from the National Vulnerability Database. Open-source package versions from OSV (CC-BY 4.0). Text is shown as each source states it; Stackurity does not edit it. Check the vendor's advisory before acting.
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