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CVE-2024-21413 Microsoft CVE debrief

CVE-2024-21413 is a Microsoft Outlook improper input validation vulnerability that CISA added to the Known Exploited Vulnerabilities catalog on 2025-02-06. That KEV listing is the key risk signal here: it means the flaw is known to be exploited in real-world environments, so affected Outlook deployments should be treated as urgent remediation candidates.

Vendor
Microsoft
Product
Office Outlook
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2025-02-06
Original CVE updated
2025-02-06
Advisory published
2025-02-06
Advisory updated
2025-02-06

Who should care

Organizations that use Microsoft Office Outlook, especially security teams, endpoint administrators, vulnerability management teams, and incident responders. Any environment that relies on Outlook for email handling should prioritize this CVE because it is on CISA’s Known Exploited Vulnerabilities list.

Technical summary

The available source corpus identifies the issue as an improper input validation vulnerability in Microsoft Outlook. CISA’s KEV entry marks it as known exploited and directs organizations to apply vendor mitigations or discontinue use if mitigations are unavailable. The corpus does not provide additional technical mechanics, exploitation preconditions, or impact details, so the safest operational interpretation is to treat it as an actively abused Outlook flaw requiring expedited remediation.

Defensive priority

High / urgent. A KEV-listed Outlook vulnerability should be prioritized ahead of routine patch work because CISA has already confirmed exploitation in the wild.

Recommended defensive actions

  • Apply Microsoft mitigations or vendor guidance as soon as possible.
  • If mitigations are unavailable, follow CISA guidance to discontinue use of the affected product until protected.
  • Prioritize affected Outlook systems in vulnerability management and patch queues.
  • Confirm which endpoints, users, and mail-processing systems run the impacted Outlook version or configuration.
  • Track remediation status until the CVE is fully addressed across the environment.

Evidence notes

This debrief is based on the supplied CISA KEV source item and the official record links provided in the corpus. The KEV metadata identifies Microsoft as the vendor, Office Outlook as the product, the vulnerability as an improper input validation issue, and the date added to KEV as 2025-02-06. The corpus also references the Microsoft Security Response Center update guide and the NVD detail page, but no additional technical details were supplied beyond the KEV entry.

Official resources

Publicly identified through the CVE record and added by CISA to the Known Exploited Vulnerabilities catalog on 2025-02-06.