Linux Kernel Privilege Escalation Vulnerability

Added to KEV
2022-10-20
Federal due date
2022-11-10
Vendor
Linux
Product
Kernel
EPSS
99.1th percentile (score 0.800, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2021-3493

CISA short 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.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.