Is CVE-2021-3995 in the CISA KEV catalog?

No. CVE-2021-3995 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-3995?

CVE-2021-3995 has a CVSS v3 base score of 5.5 (MEDIUM).

What is the EPSS score for CVE-2021-3995?

CVE-2021-3995 has an EPSS score of 0.63% (46th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-3995?

Upgrade util-linux on debian 11 to 2.36.1-8+deb11u1 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-3995

MEDIUM

5.5

CVSS v3

NVD

Description

A logic error was found in the libmount library of util-linux in the function that allows an unprivileged user to unmount a FUSE filesystem. This flaw allows an unprivileged local attacker to unmount FUSE filesystems that belong to certain other users who have a UID that is a prefix of the UID of the attacker in its string form. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.

CWE-552

How to fix

Remediation Available

util-linuxDebian

Fixed in:2.36.1-8+deb11u1CVE-2021-3995

Fixed in:2.37.3-1CVE-2021-3995

mountUbuntu

Fixed in:2.34-0.1ubuntu9.3USN-5279-1

util-linuxUbuntu

Fixed in:2.34-0.1ubuntu9.3USN-5279-1

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

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

0.63%probability of exploitation in 30 days

46thpercentile

Moderate risk: more likely to be exploited than 46% of all known CVEs.

References

Patch2

Vendor Advisory1

mirrors.edge.kernel.org

Third-Party Advisory4

Issue Tracking1

bugzilla.redhat.com

Other references1

security.gentoo.org

Related Vulnerabilities

Other CWE-552 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2020-17519	High	7.5	98%	KEV	Fix
CVE-2025-11371	High	7.5	92%	KEV	Fix
CVE-2023-50164	Critical	9.8	81%	-	Fix
CVE-2016-3715	Medium	5.5	75%	KEV	Fix
CVE-2020-15175	High	7.4	71%	-	Fix
CVE-2021-39316	High	7.5	67%	-	-

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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 2024-11-21.