#VU61246 Use-after-free in Linux kernel - CVE-2021-4083

Vulnerability identifier: #VU61246

Vulnerability risk: Low

CVSSv4.0: 4.4 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-4083

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the Linux kernel's garbage collection for Unix domain socket file handlers. A local user can call close() and fget() simultaneously and can potentially trigger a race condition, which in turn leads to a use-after-free error and allows privilege escalation.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.16, 5.16

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External links
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=054aa8d439b9
https://bugzilla.redhat.com/show_bug.cgi?id=2029923

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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.