Hazard

Is CVE-2024-21351 being exploited?

Confirmed exploited in the wild

CISA has evidence of active exploitation. This is not theoretical risk — someone has already used it against someone.

Microsoft Windows SmartScreen Security Feature Bypass Vulnerability

Microsoft · Windows

CVSS 7.6 EPSS 30% no public exploit indexed Fix deadline passed 5 March 2024

What it is

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.

Why we say that

  • CISA's federal remediation deadline (2024-03-05) has passed
  • Listed in the CISA Known Exploited Vulnerabilities catalogue

Every line above comes from a named public source. Where the evidence is thin, we say so rather than inventing confidence — see methodology.

What to do

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What it costs when this goes wrong

This is where UK enforcement meets the vulnerability record. Where an unfixed vulnerability leads to a breach, the ICO treats it as a security failure under UK GDPR. Recent cases:

All UK cases caused by unpatched software →