CVE-2021-3996

MEDIUM
5.5
CVSS Score
Published: August 23, 2022 at 12:00 AM UTC
Updated: June 17, 2026 at 04:06 AM UTC
2 products affected across 2 vendorsFedoraUtil Linux

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.6%
SSVC
PoC

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 a local user on a vulnerable system to unmount other users' filesystems that are either world-writable themselves (like /tmp) or mounted in a world-writable directory. An attacker may use this flaw to cause a denial of service to applications that use the affected filesystems.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.34 ≤ v < 2.37.3
Vendor states this is fixed in 2.37.3 (unaffected)

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.5MEDIUMCISA-ADP
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-552

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