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CVE-2021-3493

HIGH8.8
CISA KEV

Published 2021-04-17 · Updated 2026-06-17 · Source security@ubuntu.com

Summary

CVE-2021-3493 is a high-severity (CVSS 8.8) vulnerability in Linux Kernel. CISA added it to the Known Exploited Vulnerabilities catalog on October 20, 2022, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by November 10, 2022. CISA does not currently list it as used in ransomware campaigns. Linux has 32 vulnerabilities in the KEV catalog, 2 of them linked to ransomware.

All 32 known-exploited Linux vulnerabilities →

Description

The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.

CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CWE-270CWE-863

CISA Known-Exploited Vulnerability

Product: Linux — Kernel

Name: Linux Kernel Privilege Escalation Vulnerability

Date added: 2022-10-20 · Due: 2022-11-10

Required action: Apply updates per vendor instructions.

References

View on NVD