Is CVE-2021-3493 in the CISA KEV catalog?

Yes. CVE-2021-3493 is on the CISA Known Exploited Vulnerabilities list, added 2022-10-20.

What is the CVSS severity of CVE-2021-3493?

CVE-2021-3493 has a CVSS v3 base score of 8.8 (HIGH).

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

CVE-2021-3493 has an EPSS score of 43.99% (99th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3493?

Upgrade linux on debian 11 to 5.10.38-1 or later. Fixes are available for 145 affected products.

CVE & CISA-KEV Catalog

CVE-2021-3493

HIGHCISA KEVEPSS 99th pctl

8.8

CVSS v3

NVD

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.

CWE-270 CWE-863Incorrect Authorization

How to fix

Remediation Available

linuxDebian

Fixed in:5.10.38-1CVE-2021-3493

awsUbuntu

Fixed in:4.4.0-1098LSN-0076-1

Fixed in:4.15.0-1054LSN-0076-1

Fixed in:5.4.0-1009LSN-0076-1

azureUbuntu

Fixed in:4.15.0-1063LSN-0076-1

Fixed in:5.4.0-1010LSN-0076-1

gcpUbuntu

Fixed in:5.4.0-1009LSN-0076-1

generic-4.15Ubuntu

Fixed in:4.15.0-69LSN-0076-1

generic-4.4Ubuntu

Fixed in:4.4.0-168LSN-0076-1

generic-5.4Ubuntu

Fixed in:5.4.0-26LSN-0076-1

gkeUbuntu

Fixed in:5.4.0-1033LSN-0076-1

gke-4.15Ubuntu

Fixed in:4.15.0-1076LSN-0076-1

gke-5.4Ubuntu

Fixed in:5.4.0-1009LSN-0076-1

gkeopUbuntu

Fixed in:5.4.0-1009LSN-0076-1

gkeop-5.4Ubuntu

Fixed in:5.4.0-1007LSN-0076-1

linuxUbuntu

Fixed in:4.4.0-209.241USN-4916-1

Fixed in:4.15.0-142.146USN-4916-1

Fixed in:5.4.0-72.80USN-4917-1

linux-awsUbuntu

Fixed in:4.4.0-1091.95USN-4916-1

Fixed in:4.4.0-1127.141USN-4916-1

Fixed in:4.15.0-1099.106USN-4916-1

Fixed in:5.4.0-1045.47USN-4917-1

linux-aws-5.4Ubuntu

Fixed in:5.4.0-1045.47~18.04.1USN-4917-1

linux-aws-hweUbuntu

Fixed in:4.15.0-1099.106~16.04.1USN-4916-1

linux-azureUbuntu

Fixed in:4.15.0-1113.126~14.04.1USN-4916-1

Fixed in:4.15.0-1113.126~16.04.1USN-4916-1

Fixed in:5.4.0-1046.48USN-4917-1

linux-azure-4.15Ubuntu

Fixed in:4.15.0-1113.126USN-4916-1

linux-azure-5.4Ubuntu

Fixed in:5.4.0-1046.48~18.04.1USN-4917-1

linux-dell300xUbuntu

Fixed in:4.15.0-1017.21USN-4916-1

linux-gcpUbuntu

Fixed in:4.15.0-1098.111~16.04.1USN-4916-1

Fixed in:5.4.0-1042.45USN-4917-1

linux-gcp-4.15Ubuntu

Fixed in:4.15.0-1098.111USN-4916-1

linux-gcp-5.4Ubuntu

Fixed in:5.4.0-1042.45~18.04.1USN-4917-1

linux-gke-5.3Ubuntu

Fixed in:5.3.0-1042.45USN-4917-1

linux-gke-5.4Ubuntu

Fixed in:5.4.0-1042.44~18.04.1USN-4917-1

linux-gkeopUbuntu

Fixed in:5.4.0-1014.15USN-4917-1

linux-gkeop-5.4Ubuntu

Fixed in:5.4.0-1014.15~18.04.1USN-4917-1

linux-hweUbuntu

Fixed in:4.15.0-142.146~16.04.1USN-4916-1

Fixed in:5.3.0-73.69USN-4917-1

linux-hwe-5.4Ubuntu

Fixed in:5.4.0-72.80~18.04.1USN-4917-1

linux-hwe-5.8Ubuntu

Fixed in:5.8.0-50.56~20.04.1USN-4917-1

linux-image-4.15.0-1017-dell300xUbuntu

Fixed in:4.15.0-1017.21USN-4916-1

linux-image-4.15.0-1070-oracleUbuntu

Fixed in:4.15.0-1070.78~16.04.1USN-4916-1

Fixed in:4.15.0-1070.78USN-4916-1

linux-image-4.15.0-1084-raspi2Ubuntu

Fixed in:4.15.0-1084.89USN-4916-1

linux-image-4.15.0-1090-kvmUbuntu

Fixed in:4.15.0-1090.92USN-4916-1

linux-image-4.15.0-1098-gcpUbuntu

Fixed in:4.15.0-1098.111~16.04.1USN-4916-1

Fixed in:4.15.0-1098.111USN-4916-1

linux-image-4.15.0-1099-awsUbuntu

Fixed in:4.15.0-1099.106~16.04.1USN-4916-1

Fixed in:4.15.0-1099.106USN-4916-1

linux-image-4.15.0-1101-snapdragonUbuntu

Fixed in:4.15.0-1101.110USN-4916-1

linux-image-4.15.0-1113-azureUbuntu

Fixed in:4.15.0-1113.126~14.04.1USN-4916-1

Fixed in:4.15.0-1113.126~16.04.1USN-4916-1

Fixed in:4.15.0-1113.126USN-4916-1

linux-image-4.15.0-142-genericUbuntu

Fixed in:4.15.0-142.146~16.04.1USN-4916-1

Fixed in:4.15.0-142.146USN-4916-1

linux-image-4.15.0-142-generic-lpaeUbuntu

Fixed in:4.15.0-142.146~16.04.1USN-4916-1

Fixed in:4.15.0-142.146USN-4916-1

linux-image-4.15.0-142-lowlatencyUbuntu

Fixed in:4.15.0-142.146~16.04.1USN-4916-1

Fixed in:4.15.0-142.146USN-4916-1

linux-image-4.4.0-1091-awsUbuntu

Fixed in:4.4.0-1091.95USN-4916-1

linux-image-4.4.0-1092-kvmUbuntu

Fixed in:4.4.0-1092.101USN-4916-1

linux-image-4.4.0-1127-awsUbuntu

Fixed in:4.4.0-1127.141USN-4916-1

linux-image-4.4.0-1151-raspi2Ubuntu

Fixed in:4.4.0-1151.162USN-4916-1

linux-image-4.4.0-1155-snapdragonUbuntu

Fixed in:4.4.0-1155.165USN-4916-1

linux-image-4.4.0-209-genericUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-4.4.0-209-generic-lpaeUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-4.4.0-209-lowlatencyUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-4.4.0-209-powerpc-e500mcUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-4.4.0-209-powerpc-smpUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-4.4.0-209-powerpc64-embUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-4.4.0-209-powerpc64-smpUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

Fixed in:4.4.0-209.241USN-4916-1

linux-image-5.10.0-1022-oemUbuntu

Fixed in:5.10.0-1022.23USN-4917-1

linux-image-5.3.0-1039-raspi2Ubuntu

Fixed in:5.3.0-1039.41USN-4917-1

linux-image-5.3.0-1042-gkeUbuntu

Fixed in:5.3.0-1042.45USN-4917-1

linux-image-5.3.0-73-genericUbuntu

Fixed in:5.3.0-73.69USN-4917-1

linux-image-5.3.0-73-lowlatencyUbuntu

Fixed in:5.3.0-73.69USN-4917-1

linux-image-5.4.0-1014-gkeopUbuntu

Fixed in:5.4.0-1014.15~18.04.1USN-4917-1

Fixed in:5.4.0-1014.15USN-4917-1

linux-image-5.4.0-1034-raspiUbuntu

Fixed in:5.4.0-1034.37~18.04.1USN-4917-1

Fixed in:5.4.0-1034.37USN-4917-1

linux-image-5.4.0-1038-kvmUbuntu

Fixed in:5.4.0-1038.39USN-4917-1

linux-image-5.4.0-1042-gcpUbuntu

Fixed in:5.4.0-1042.45~18.04.1USN-4917-1

Fixed in:5.4.0-1042.45USN-4917-1

linux-image-5.4.0-1042-gkeUbuntu

Fixed in:5.4.0-1042.44~18.04.1USN-4917-1

linux-image-5.4.0-1043-oracleUbuntu

Fixed in:5.4.0-1043.46~18.04.1USN-4917-1

Fixed in:5.4.0-1043.46USN-4917-1

linux-image-5.4.0-1045-awsUbuntu

Fixed in:5.4.0-1045.47~18.04.1USN-4917-1

Fixed in:5.4.0-1045.47USN-4917-1

linux-image-5.4.0-1046-azureUbuntu

Fixed in:5.4.0-1046.48~18.04.1USN-4917-1

Fixed in:5.4.0-1046.48USN-4917-1

linux-image-5.4.0-72-genericUbuntu

Fixed in:5.4.0-72.80~18.04.1USN-4917-1

Fixed in:5.4.0-72.80USN-4917-1

linux-image-5.4.0-72-generic-lpaeUbuntu

Fixed in:5.4.0-72.80~18.04.1USN-4917-1

Fixed in:5.4.0-72.80USN-4917-1

linux-image-5.4.0-72-lowlatencyUbuntu

Fixed in:5.4.0-72.80~18.04.1USN-4917-1

Fixed in:5.4.0-72.80USN-4917-1

linux-image-5.6.0-1054-oemUbuntu

Fixed in:5.6.0-1054.58USN-4915-1

linux-image-5.8.0-50-genericUbuntu

Fixed in:5.8.0-50.56~20.04.1USN-4917-1

linux-image-5.8.0-50-generic-64kUbuntu

Fixed in:5.8.0-50.56~20.04.1USN-4917-1

linux-image-5.8.0-50-generic-lpaeUbuntu

Fixed in:5.8.0-50.56~20.04.1USN-4917-1

linux-image-5.8.0-50-lowlatencyUbuntu

Fixed in:5.8.0-50.56~20.04.1USN-4917-1

linux-image-awsUbuntu

Fixed in:4.4.0.1091.88USN-4916-1

Fixed in:4.4.0.1127.132USN-4916-1

Fixed in:5.4.0.1045.27USN-4917-1

Fixed in:5.4.0.1045.46USN-4917-1

linux-image-aws-hweUbuntu

Fixed in:4.15.0.1099.92USN-4916-1

linux-image-aws-lts-18.04Ubuntu

Fixed in:4.15.0.1099.102USN-4916-1

linux-image-azureUbuntu

Fixed in:4.15.0.1113.86USN-4916-1

Fixed in:4.15.0.1113.104USN-4916-1

Fixed in:5.4.0.1046.25USN-4917-1

Fixed in:5.4.0.1046.44USN-4917-1

linux-image-azure-lts-18.04Ubuntu

Fixed in:4.15.0.1113.86USN-4916-1

linux-image-dell300xUbuntu

Fixed in:4.15.0.1017.19USN-4916-1

linux-image-gcpUbuntu

Fixed in:4.15.0.1098.99USN-4916-1

Fixed in:5.4.0.1042.29USN-4917-1

Fixed in:5.4.0.1042.51USN-4917-1

linux-image-gcp-lts-18.04Ubuntu

Fixed in:4.15.0.1098.116USN-4916-1

linux-image-genericUbuntu

Fixed in:4.4.0.209.215USN-4916-1

Fixed in:4.15.0.142.129USN-4916-1

Fixed in:5.4.0.72.75USN-4917-1

linux-image-generic-64k-hwe-20.04Ubuntu

Fixed in:5.8.0.50.56~20.04.34USN-4917-1

linux-image-generic-hwe-16.04Ubuntu

Fixed in:4.15.0.142.137USN-4916-1

linux-image-generic-hwe-18.04Ubuntu

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

linux-image-generic-hwe-20.04Ubuntu

Fixed in:5.8.0.50.56~20.04.34USN-4917-1

linux-image-generic-lpaeUbuntu

Fixed in:4.4.0.209.215USN-4916-1

Fixed in:4.15.0.142.129USN-4916-1

Fixed in:5.4.0.72.75USN-4917-1

linux-image-generic-lpae-hwe-16.04Ubuntu

Fixed in:4.15.0.142.137USN-4916-1

linux-image-generic-lpae-hwe-18.04Ubuntu

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

linux-image-generic-lpae-hwe-20.04Ubuntu

Fixed in:5.8.0.50.56~20.04.34USN-4917-1

linux-image-generic-lpae-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-generic-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-gkeUbuntu

Fixed in:4.15.0.1098.99USN-4916-1

linux-image-gke-5.3Ubuntu

Fixed in:5.3.0.1042.25USN-4917-1

linux-image-gke-5.4Ubuntu

Fixed in:5.4.0.1042.44~18.04.8USN-4917-1

linux-image-gkeopUbuntu

Fixed in:5.4.0.1014.17USN-4917-1

linux-image-gkeop-5.3Ubuntu

Fixed in:5.3.0.73.130USN-4917-1

linux-image-gkeop-5.4Ubuntu

Fixed in:5.4.0.1014.15~18.04.15USN-4917-1

Fixed in:5.4.0.1014.17USN-4917-1

linux-image-kvmUbuntu

Fixed in:4.4.0.1092.90USN-4916-1

Fixed in:4.15.0.1090.86USN-4916-1

Fixed in:5.4.0.1038.36USN-4917-1

linux-image-lowlatencyUbuntu

Fixed in:4.4.0.209.215USN-4916-1

Fixed in:4.15.0.142.129USN-4916-1

Fixed in:5.4.0.72.75USN-4917-1

linux-image-lowlatency-hwe-16.04Ubuntu

Fixed in:4.15.0.142.137USN-4916-1

linux-image-lowlatency-hwe-18.04Ubuntu

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

linux-image-lowlatency-hwe-20.04Ubuntu

Fixed in:5.8.0.50.56~20.04.34USN-4917-1

linux-image-lowlatency-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-oemUbuntu

Fixed in:4.15.0.142.137USN-4916-1

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

Fixed in:5.4.0.72.75USN-4917-1

linux-image-oem-20.04Ubuntu

Fixed in:5.6.0.1054.50USN-4915-1

linux-image-oem-20.04bUbuntu

Fixed in:5.10.0.1022.23USN-4917-1

linux-image-oem-osp1Ubuntu

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

Fixed in:5.4.0.72.75USN-4917-1

linux-image-oracleUbuntu

Fixed in:4.15.0.1070.58USN-4916-1

Fixed in:5.4.0.1043.46~18.04.25USN-4917-1

Fixed in:5.4.0.1043.40USN-4917-1

linux-image-oracle-lts-18.04Ubuntu

Fixed in:4.15.0.1070.80USN-4916-1

linux-image-powerpc-e500mcUbuntu

Fixed in:4.4.0.209.215USN-4916-1

linux-image-powerpc-e500mc-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-powerpc-smpUbuntu

Fixed in:4.4.0.209.215USN-4916-1

linux-image-powerpc-smp-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-powerpc64-embUbuntu

Fixed in:4.4.0.209.215USN-4916-1

linux-image-powerpc64-emb-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-powerpc64-smpUbuntu

Fixed in:4.4.0.209.215USN-4916-1

linux-image-powerpc64-smp-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-image-raspiUbuntu

Fixed in:5.4.0.1034.69USN-4917-1

linux-image-raspi-hwe-18.04Ubuntu

Fixed in:5.4.0.1034.36USN-4917-1

linux-image-raspi2Ubuntu

Fixed in:4.4.0.1151.151USN-4916-1

Fixed in:4.15.0.1084.81USN-4916-1

Fixed in:5.4.0.1034.69USN-4917-1

linux-image-raspi2-hwe-18.04Ubuntu

Fixed in:5.3.0.1039.28USN-4917-1

linux-image-snapdragonUbuntu

Fixed in:4.4.0.1155.147USN-4916-1

Fixed in:4.15.0.1101.104USN-4916-1

linux-image-snapdragon-hwe-18.04Ubuntu

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

linux-image-virtualUbuntu

Fixed in:4.4.0.209.215USN-4916-1

Fixed in:4.15.0.142.129USN-4916-1

Fixed in:5.4.0.72.75USN-4917-1

linux-image-virtual-hwe-16.04Ubuntu

Fixed in:4.15.0.142.137USN-4916-1

linux-image-virtual-hwe-18.04Ubuntu

Fixed in:5.4.0.72.80~18.04.65USN-4917-1

linux-image-virtual-hwe-20.04Ubuntu

Fixed in:5.8.0.50.56~20.04.34USN-4917-1

linux-image-virtual-lts-xenialUbuntu

Fixed in:4.4.0.209.182USN-4916-1

linux-kvmUbuntu

Fixed in:4.4.0-1092.101USN-4916-1

Fixed in:4.15.0-1090.92USN-4916-1

Fixed in:5.4.0-1038.39USN-4917-1

linux-lts-xenialUbuntu

Fixed in:4.4.0-209.241~14.04.1USN-4916-1

linux-oem-5.10Ubuntu

Fixed in:5.10.0-1022.23USN-4917-1

linux-oem-5.6Ubuntu

Fixed in:5.6.0-1054.58USN-4915-1

linux-oracleUbuntu

Fixed in:4.15.0-1070.78~16.04.1USN-4916-1

Fixed in:4.15.0-1070.78USN-4916-1

Fixed in:5.4.0-1043.46USN-4917-1

linux-oracle-5.4Ubuntu

Fixed in:5.4.0-1043.46~18.04.1USN-4917-1

linux-raspiUbuntu

Fixed in:5.4.0-1034.37USN-4917-1

linux-raspi-5.4Ubuntu

Fixed in:5.4.0-1034.37~18.04.1USN-4917-1

linux-raspi2Ubuntu

Fixed in:4.4.0-1151.162USN-4916-1

Fixed in:4.15.0-1084.89USN-4916-1

linux-raspi2-5.3Ubuntu

Fixed in:5.3.0-1039.41USN-4917-1

linux-snapdragonUbuntu

Fixed in:4.4.0-1155.165USN-4916-1

Fixed in:4.15.0-1101.110USN-4916-1

lowlatency-4.15Ubuntu

Fixed in:4.15.0-69LSN-0076-1

lowlatency-4.4Ubuntu

Fixed in:4.4.0-168LSN-0076-1

lowlatency-5.4Ubuntu

Fixed in:5.4.0-26LSN-0076-1

oemUbuntu

Fixed in:4.15.0-1063LSN-0076-1

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

43.99%probability of exploitation in 30 days

99thpercentile

Very high risk: more likely to be exploited than 99% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Linux Kernel Privilege Escalation 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.

Apply updates per vendor instructions.

Remediation due: 2022-11-10

References

Patch1

git.kernel.org

Exploit2

Vendor Advisory1

ubuntu.com

Third-Party Advisory2

Government Resource1

cisa.gov

Related Vulnerabilities

Other CWE-270 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-26475	Critical	9.9	65%	-	Fix
CVE-2023-25754	Critical	9.8	2.3%	-	Fix
CVE-2023-37912	Critical	9.9	1.2%	-	Fix
CVE-2020-7019	Medium	6.5	1.2%	-	Fix
CVE-2019-14819	High	8.8	1.1%	-	-
CVE-2020-7020	Low	3.1	1.0%	-	Fix

Embed a live status badge for CVE-2021-3493

Markdown

[![CVE-2021-3493](https://tridentstack.com/cve/badge/CVE-2021-3493.svg)](https://tridentstack.com/cve/CVE-2021-3493)

HTML

<a href="https://tridentstack.com/cve/CVE-2021-3493"><img src="https://tridentstack.com/cve/badge/CVE-2021-3493.svg" alt="CVE-2021-3493"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

See how it works Start freeThis CVE lookup is free and always will be.

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-28.