← Back to CVEs

CVE-2021-3493

HIGHCISA KEV

8.8

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.

CVE Details

CVSS v3.1 Score8.8

SeverityHIGH

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

Attack VectorLOCAL

ComplexityLOW

Privileges RequiredLOW

User InteractionNONE

Published4/17/2021

Last Modified10/28/2025

Sourcekev

Honeypot Sightings0

CISA KEV

VendorLinux

ProductKernel

Vulnerability NameLinux Kernel Privilege Escalation Vulnerability

KEV Date Added2022-10-20

Remediation Due Date2022-11-10

Ransomware UseUnknown

Affected Products

canonical:ubuntu_linux

Weaknesses (CWE)

CWE-270CWE-863

References

http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html(security@ubuntu.com)

http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html(security@ubuntu.com)

http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html(security@ubuntu.com)

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52(security@ubuntu.com)

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

https://www.openwall.com/lists/oss-security/2021/04/16/1(security@ubuntu.com)

http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html(af854a3a-2127-422b-91ae-364da2661108)

http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html(af854a3a-2127-422b-91ae-364da2661108)

http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html(af854a3a-2127-422b-91ae-364da2661108)

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52(af854a3a-2127-422b-91ae-364da2661108)

https://ubuntu.com/security/notices/USN-4917-1(af854a3a-2127-422b-91ae-364da2661108)

https://www.openwall.com/lists/oss-security/2021/04/16/1(af854a3a-2127-422b-91ae-364da2661108)

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-3493(134c704f-9b21-4f2e-91b3-4a467353bcc0)

IOC Correlations

No correlations recorded

This product uses data from the NVD API but is not endorsed or certified by the NVD.