All vulnerabilities
CVE-2021-3493

Linux Kernel Privilege Escalation Vulnerability

Linux KernelOperating systems
Open in ThreatlineRecord JSON
CVSS
8.8High
ExploitationExploited in the wildAdded to KEV 20 Oct 2022CISA KEV
Exploit odds (EPSS)49.2%Chance of exploitation activity in the next 30 days, higher than 98% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in5.8.0-50.56Also 5.4.0-72.80, 4.15.0-142.146 and 1 moreCVE List
Federal deadline10 Nov 2022Remediation due date for US federal agenciesCISA KEV
CISA required actionApply updates per vendor instructions. CISA KEV

What fixes it

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Timeline

  1. 12 Apr 2021Exploit code publicMetasploit
  2. 17 Apr 2021, 04:20 UTCPublishedCVE List
  3. 20 Oct 2022Added to CISA KEVCISA KEV

Public exploit code and templates 1

  • Exploit module2021 Ubuntu Overlayfs LPE 12 Apr 2021Metasploit

Listed so defenders can prioritize. Threatline links to the source and does not host exploit code.

Description

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.

Text from CVE List

Affected versions 4

  • linux kernelaffected: 5.8 kernel before 5.8.0-50.56CVE List
  • linux kernelaffected: 5.4 kernel before 5.4.0-72.80CVE List
  • linux kernelaffected: 4.15 kernel before 4.15.0-142.146CVE List
  • linux kernelaffected: 4.4 kernel before 4.4.0-209.241CVE List

References 5