CVE-2021-3493

high
New! CVE Severity Now Using CVSS v3

The calculated severity for CVEs has been updated to use CVSS v3 by default. CVEs that do not have a CVSS v3 score will fall back CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

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.

References

https://www.openwall.com/lists/oss-security/2021/04/16/1

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52

https://ubuntu.com/security/notices/USN-4917-1

http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html

http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html

http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html

Details

Source: MITRE

Published: 2021-04-17

Updated: 2021-12-16

Type: CWE-269

Risk Information

CVSS v2

Base Score: 7.2

Vector: AV:L/AC:L/Au:N/C:C/I:C/A:C

Impact Score: 10

Exploitability Score: 3.9

Severity: HIGH

CVSS v3

Base Score: 7.8

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

Impact Score: 5.9

Exploitability Score: 1.8

Severity: HIGH

Tenable Plugins

View all (3 total)

IDNameProductFamilySeverity
148691Ubuntu 16.04 LTS / 18.04 LTS : Linux kernel vulnerabilities (USN-4916-1)NessusUbuntu Local Security Checks
high
148690Ubuntu 18.04 LTS / 20.04 LTS / 20.10 : Linux kernel vulnerabilities (USN-4917-1)NessusUbuntu Local Security Checks
high
148689Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-4915-1)NessusUbuntu Local Security Checks
high