CVE-2021-4090 Memory corruption in kernel

What is CVE-2021-4090?

CVE-2021-4090 is a high-severity memory corruption vulnerability in Linux kernel, published on 18 Feb 2022. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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.

Weakness: CWE-787

Which versions are affected by CVE-2021-4090?

It affects 9 products.

Products include Linux kernel, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500e Firmware and 3 more.

How do I fix CVE-2021-4090?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-4090 being exploited?

There is no known exploitation of CVE-2021-4090 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-8654, DEBIAN-CVE-2021-4090, GHSA-rwxr-f4qj-9x36, UBUNTU-CVE-2021-4090.