Is CVE-2021-3493 actively exploited?

CVE-2021-3493 has no public evidence of in-the-wild exploitation as of 2025-10-28.

What is the CVSS score for CVE-2021-3493?

CVE-2021-3493 has a CVSS score of 8.8 (HIGH severity). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

How do I patch CVE-2021-3493?

Patch guidance is available from canonical security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2021-3493.

Fix CVE-2021-3493 - HIGH canonical ubuntu linux

Q: Which products are affected by CVE-2021-3493?

3 products: canonical ubuntu linux, canonical ubuntu linux, canonical ubuntu linux.

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 Metrics

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Attack Vector: local
Complexity: low
Privileges: low
User Action: none
Scope: changed
Confidentiality: high
Integrity: high
Availability: high
Weaknesses: CWE-270 CWE-863 · Incorrect Authorization

Metadata

Primary Vendor: CANONICAL
Published: 4/17/2021
Last Modified: 10/28/2025
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

CVE-2021-3493

Description

CVSS Metrics

Metadata

Affected Products

Remediation Guidance

Executive Summary