8.8

CVE-2021-3493

Warning
Exploit

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.

Data is provided by the National Vulnerability Database (NVD)
Canonical ≫ Ubuntu Linux SwEditionlts Version < 18.04
Canonical ≫ Ubuntu Linux SwEditionlts Version >= 18.04.1 < 20.04
Canonical ≫ Ubuntu Linux SwEdition- Version < 20.10

20.10.2022: CISA Known Exploited Vulnerabilities (KEV) Catalog

Linux Kernel Privilege Escalation Vulnerability

Vulnerability

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.

Description

Apply updates per vendor instructions.

Required actions
EPSS Metriken
Type Source Score Percentile
EPSS FIRST.org 75.34% 0.988
CVSS Metriken
Source Base Score Exploit Score Impact Score Vector string
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvd@nist.gov 7.2 3.9 10
AV:L/AC:L/Au:N/C:C/I:C/A:C
security@ubuntu.com 8.8 2 6
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE-270 Privilege Context Switching Error

The product does not properly manage privileges while it is switching between different contexts that have different privileges or spheres of control.

CWE-863 Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.