Denial of service in Linux kernel NFSv4 implementation

1) Race condition

EUVDB-ID: #VU61208

Risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-38199

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Exploit availability: No

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

External links

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

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.