CVE-2024-21413
Microsoft Outlook Improper Input Validation Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 27 February 2025). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
Microsoft Outlook Remote Code Execution Vulnerability
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 94.66% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 6 February 2025 · due 27 February 2025
- Weakness
- CWE-20
- Affected
- microsoft/365 apps · microsoft/office 2016 · microsoft/office 2019 · microsoft/office long term servicing channel
- Source
- secure@microsoft.com
EPSS 94.7% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable. https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413 ; https://nvd.nist.gov/vuln/detail/CVE-2024-21413
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413Patch, Vendor Advisory
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413Patch, 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-scriptExploit
- https://www.vicarius.io/vsociety/posts/cve-2024-21413-critical-monikerlink-vulnerability-affecting-microsoft-outlook-mitigation-scriptMitigation
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21413US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.