CVE-2024-21351: Microsoft Windows SmartScreen Security Feature Bypass Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 13 Feb 2024, the same day the CVE record was published.

How likely is exploitation in the next 30 days?

27.8%

EPSS score, percentile 98.1 of all scored records

How severe?

7.6 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline 5 Mar 2024. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Advisories and patches (1)

Which versions are affected?

Affected

• from 10.0.10240.0 to before 10.0.10240.20469
• from 10.0.14393.0 to before 10.0.14393.6709
• from 10.0.17763.0 to before 10.0.17763.5458
• from 10.0.0 to before 10.0.17763.5458
• from 10.0.19043.0 to before 10.0.19044.4046
• from 10.0.19045.0 to before 10.0.19045.4046

and 7 more in the table below

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 5 March 2024.

Advisories and patches

• Windows SmartScreen Security Feature Bypass Vulnerability (Vendor advisory, Patch)

Linked from CISA's catalog entry

• https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2024-21351
• https://nvd.nist.gov/vuln/detail/CVE-2024-21351

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Microsoft Windows SmartScreen contains a security feature bypass vulnerability that allows an attacker to bypass the SmartScreen user experience and inject code to potentially gain code execution, which could lead to some data exposure, lack of system availability, or both.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2024-21351 to its Known Exploited Vulnerabilities (KEV) catalog on 13 Feb 2024.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 5 Mar 2024.
• The CVE record was published on 13 Feb 2024, the same day it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.6 (High), given by its CNA.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 27.8% (percentile 98.1), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Windows SmartScreen Security Feature Bypass Vulnerability

Windows SmartScreen Security Feature Bypass Vulnerability

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-94: Improper Control of Generation of Code ('Code Injection')

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

More exploited Microsoft vulnerabilities

• CVE-2026-96951: Microsoft Windows Command Injection Vulnerability (added 13 Oct 2026)
• CVE-2026-65660: Microsoft SharePoint Code Injection Vulnerability (added 25 Sep 2026)
• CVE-2026-81963: Microsoft Windows Link Following Vulnerability (added 8 Sep 2026)
• CVE-2026-85880: Microsoft Windows Heap-Based Buffer Overflow Vulnerability (added 8 Sep 2026)
• CVE-2019-1068: Microsoft SQL Server Remote Code Execution Vulnerability (added 26 Aug 2026)
• CVE-2026-33824: Microsoft Internet Key Exchange (IKE) Service Extensions Double Free Vulnerability (added 18 Aug 2026)