Exploited vulnerability · CISA KEV

Is CVE-2024-21413 exploited? Yes: in CISA KEV since 6 Feb 2025

Gociux · Microsoft Office Outlook · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2024-21413, Microsoft Outlook Improper Input Validation Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 6 Feb 2025, 359 days after it was published. It affects Microsoft Office Outlook. If you run it, CISA's required action is: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What it is

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.

What to do

1. Check whether you run it. Look for Office Outlook in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
2. Apply the fix. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 13 Feb 2024.
4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21413
• nvd.nist.gov/vuln/detail/CVE-2024-21413

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in February 2025 · Microsoft scorecard · act-now radar.