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CVE-2021-3493

Published: Apr 17, 2021Updated: Oct 28, 2025 Sources: CVE List NVD BDUCWE-270
NVD MITRE
8.8CVSSHIGH
EPSS Score
44.0%
Top 1.4%
CISA KEV
Active Exploitation
Since Oct 20, 2022
Exploits
4 Known
Remediation
Patch Available

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 Vector Breakdown

AV:LAC:LPR:LUI:NS:CC:HI:HA:H
Exploitability
AV:LAttack Vector
Local
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-270CWE-863

Affected Products

Debian GNU/LinuxСообщество свободного программного обеспечения
On-premOS
Operating Systems / linux-distro
Astra Linux Special EditionООО «РусБИТех-Астра»
On-premOS
Operating Systems / linux-distro
LinuxСообщество свободного программного обеспечения
On-premOS
Operating Systems / linux-distro
ОСОН ОСнова ОnyxАО «НППКТ»
On-premOS
Operating Systems / linux-distro
linux kernelUbuntu
On-prem
Operating Systems / linux-distro
сообщество свободного программного обеспеченияoss-projectOperating Systemsaka сообщество свободного программного обеспечения, fsf
ооо «русбитех-астра»commercialRUOperating Systemsaka rusbitech-astra
ао «нппкт»commercialRUOperating Systems
ubuntucommercialGBOperating Systemsaka ubuntu linux
and 1 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:Oct 20, 2022
Remediation due:Nov 10, 2022

Required action: Apply updates per vendor instructions.

4 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Workaround Available

MITRE ATT&CK

2 techniques
Initial Access
View detailed technique mapping

References

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52
git.kernel.org
https://github.com/briskets/CVE-2021-3493
github.com
https://nvd.nist.gov/vuln/detail/CVE-2021-3493
nvd.nist.gov
and 13 more references View all →

Timeline

Published
Apr 17, 2021
Added to CISA KEV
Oct 20, 2022
Last Updated
Oct 28, 2025

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