Medium severity · published Aug 23, 2022
CVE-2021-3995
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
5.5
CVSS
0.6%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 50% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FE
Fedora · Fedoraproject
35 · source: NVD
UT
Util-linux · Kernel
2.34 before 2.37.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3995
CVE.org
https://www.cve.org/CVERecord?id=CVE-2021-3995
Third Party Advisory
http://packetstormsecurity.com/files/170176/snap-confine-must_mkdir_and_open_with_perms-Race-Condition.html
Mailing List
http://seclists.org/fulldisclosure/2022/Dec/4
Mailing List
http://www.openwall.com/lists/oss-security/2022/11/30/2
Broken Link
https://bugzilla.redhat.com/show_bug.cgi?id=2024631https://access.redhat.com/security/cve/CVE-2021-3995
Patch
https://github.com/util-linux/util-linux/commit/57202f5713afa2af20ffbb6ab5331481d0396f8d
Release Notes
https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes
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