Hazard

Is CVE-2021-3493 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.

Linux Kernel Privilege Escalation Vulnerability

Linux · Kernel

CVSS 8.8 EPSS 44% no public exploit indexed Fix deadline passed 10 November 2022

What it is

The overlayfs stacking file system in Linux kernel does not properly validate the application of file capabilities against user namespaces, which could lead to privilege escalation.

Why we say that

  • CISA's federal remediation deadline (2022-11-10) 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 updates per vendor instructions.

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 →