#VU61208 Race condition in Linux kernel - CVE-2021-38199

Vulnerability identifier: #VU61208

Vulnerability risk: Low

CVSSv4.0: 1.3 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-38199

CWE-ID: CWE-362

Exploitation vector: Local network

Exploit availability: No

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

Vendor: Linux Foundation

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to fs/nfs/nfs4client.c in the Linux kernel has incorrect connection-setup ordering. A remote attacker with access to a remote NFSv4 server can perform a denial of service (DoS) attack by arranging the server to be unreachable during trunking detection.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.13.4, 5.13.4

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External links
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.4
https://github.com/torvalds/linux/commit/dd99e9f98fbf423ff6d365b37a98e8879170f17c
https://security.netapp.com/advisory/ntap-20210902-0010/
https://www.debian.org/security/2021/dsa-4978
https://lists.debian.org/debian-lts-announce/2021/10/msg00010.html
https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

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