#VU81665 Race condition in Linux kernel - CVE-2021-4001

Vulnerability identifier: #VU81665

Vulnerability risk: Low

CVSSv4.0: 1.9 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-4001

CWE-ID: CWE-362

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 race condition in kernel/bpf/syscall.c in Linux kernel ebpf. A local user can exploit the race between bpf_map_update_elem and bpf_map_freeze and modify the frozen mapped address space.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.16, 5.16

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=2025645
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=353050be4c19e102178ccc05988101887c25ae53

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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.