#VU60004 Permissions, Privileges, and Access Controls in Util-linux - CVE-2021-3995

Vulnerability identifier: #VU60004

Vulnerability risk: Low

CVSSv4.0: 1.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-3995

CWE-ID: CWE-264

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Util-linux
Universal components / Libraries / Libraries used by multiple products

Vendor: kernel.org

Description

The vulnerability allows a local user to bypass implemented security restrictions.

The vulnerability exists due to improper parsing of the /proc/self/mountinfo file in libmount. A local user can unmount other user's filesystems that are either world-writable themselves or mounted in a world-writable directory.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Util-linux: 2.2 - 2.37.2

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External links
https://www.openwall.com/lists/oss-security/2022/01/24/2
https://mirrors.edge.kernel.org/pub/linux/utils/util-linux/v2.37/v2.37.3-ReleaseNotes

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.