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Known exploited vulnerability

CVE-2021-3493

highCVSS 3.1 7.8In CISA KEVEPSS 49%Published · Ubuntu

The short answer

CVE-2021-3493 affects Ubuntu linux kernel and is rated high (CVSS 7.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2022-10-20: attackers are using it, so patch it first. The vendor has linked a patch.

What it is

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.

Weakness: CWE-270, CWE-863.

Severity

7.8 high

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

Exploited (CISA KEV)

Yes, since Oct 20, 2022

Federal due date Nov 10, 2022

EPSS, next 30 days

49%

Higher than 99% of scored CVEs

How it can be exploited

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

What CISA says to do

Apply updates per vendor instructions.

Affected products

linux kernel. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2021-3493 being exploited?

Yes. CISA added CVE-2021-3493 to its Known Exploited Vulnerabilities catalog on 2022-10-20, with a federal remediation due date of 2022-11-10.

How do I fix CVE-2021-3493?

CISA's required action: Apply updates per vendor instructions.

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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