CVE-2021-4090

An out-of-bounds (OOB) memory write flaw was found in the NFSD in the Linux kernel. Missing sanity may lead to a write beyond bmval[bmlen-1] in nfsd4_decode_bitmap4 in fs/nfsd/nfs4xdr.c. In this flaw, a local attacker with user privilege may gain access to out-of-bounds memory, leading to a system integrity and confidentiality threat.

What this means for your business

It affects Linux Kernel. It matters if your company, or a supplier that handles your data, runs it.
An attacker can use it only with access to the machine itself, with an ordinary user login, and without anyone at your company clicking anything.
FIRST's prediction model gives it a 0.3% chance of attack attempts being seen in the next 30 days, ranking above 27% of all known flaws.

What to do

1Check whether your company or your suppliers run Linux Kernel, and which version. The affected versions are listed further down this page.
2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS: 7.1 (v3.1)
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness: CWE-787
Assigned by: secalert@redhat.com

Dates

Published: 2022-02-18
Last modified: 2026-08-25
Sources: NVD

Affected products

Linux Linux Kernel- 5.16, 5.16
Netapp H300s Firmwareall versions
Netapp H300sall versions
Netapp H500s Firmwareall versions
Netapp H500sall versions
Netapp H700s Firmwareall versions
Netapp H700sall versions
Netapp H300e Firmwareall versions
Netapp H300eall versions
Netapp H500e Firmwareall versions
Netapp H500eall versions
Netapp H700e Firmwareall versions

As listed in the NVD configuration data. Not a statement about your estate.