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PatchSiren cyber security CVE debrief

CVE-2024-21351 Microsoft CVE debrief

CVE-2024-21351 is a Microsoft Windows SmartScreen security feature bypass that was published on 2024-02-13 and added to CISA’s Known Exploited Vulnerabilities catalog the same day. Because CISA tracks it as known exploited, defenders should treat it as a high-priority Windows issue and follow Microsoft’s guidance promptly.

Vendor
Microsoft
Product
Windows
CVSS
HIGH 7.6
CISA KEV
Listed
Original CVE published
2024-02-13
Original CVE updated
2024-02-13
Advisory published
2024-02-13
Advisory updated
2024-02-13

Who should care

Windows administrators, endpoint security teams, IT operations, and organizations that rely on SmartScreen protections for user endpoints should pay close attention, especially where users regularly open downloaded files or other internet-sourced content.

Technical summary

The available source material identifies the issue only as a SmartScreen security feature bypass in Microsoft Windows. CISA’s KEV catalog lists it as a known exploited vulnerability, with a required-action deadline of 2024-03-05. No CVSS score, affected-version list, or attack-chain details were provided in the supplied corpus, so the safest interpretation is that this is a Microsoft-tracked Windows security bypass requiring vendor remediation guidance.

Defensive priority

High. KEV inclusion indicates active exploitation, so remediation should be prioritized over routine patch cycles.

Recommended defensive actions

  • Review Microsoft’s security update guidance for CVE-2024-21351 and apply the recommended mitigation or patch as soon as possible.
  • Prioritize Windows endpoints that are internet-facing or routinely handle external downloads and attachments.
  • Validate whether any compensating controls are available if immediate remediation is not possible, and deploy them quickly.
  • Track CISA’s KEV deadline context (due date 2024-03-05) and confirm remediation before then wherever possible.
  • Monitor endpoint detections and user reports for suspicious downloaded content or unusual bypass-related activity while remediation is underway.

Evidence notes

This debrief is intentionally limited to the supplied corpus and official links. The source data identifies the vulnerability as a Microsoft Windows SmartScreen Security Feature Bypass Vulnerability, published on 2024-02-13, and CISA KEV metadata marks it as known exploited with dateAdded 2024-02-13 and dueDate 2024-03-05. No CVSS score, affected build list, or exploit details were included in the provided materials.

Sources and references

Verified primary and authoritative sources

  • CVE-2024-21351 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2024-21351

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2024-21351 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2024-21351

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.