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Linux · Kernel

CVE-2021-3493

Linux Kernel Privilege Escalation Vulnerability

CISA KEV record

CISA date added
2022-10-20
CISA due date
2022-11-10
Known ransomware use
Unknown

NVD risk context

7.8 HIGH

CVSS is a technical severity score. CISA’s KEV status remains the evidence that this vulnerability is known to be exploited.

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Attack vector
Local
An attacker needs local access to the affected system.
Attack complexity
Low
Exploitation does not require unusual conditions beyond normal attacker control.
Privileges required
Low
The attacker needs limited privileges before exploiting the issue.
User interaction
None
No action by another user is required.

Description

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.

Required action

Apply updates per vendor instructions.

NVD reference index

Vendor and remediation references

NVD has tagged these sources as vendor advisories, patches, mitigations, or release notes.

Other NVD references (5)

MITRE CWE context

CWE classification

CWE-862 Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action.

View official MITRE CWE details ↗

NVD record timing

NVD record timeline

These dates describe NVD’s record, not CISA’s KEV addition or remediation due date.

NVD published
Apr 17, 2021, 05:15 AM UTC
When NVD first published this CVE record.
NVD last updated
Jun 17, 2026, 04:05 AM UTC
When NVD last changed its analysis or record data.
Advanced: view the technical CVSS vector

This standardized code is intended for security tools and technical analysts. The plain-language risk summary above explains its main points.

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

View NVD record ↗

CISA notes

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52; https://nvd.nist.gov/vuln/detail/CVE-2021-3493