CVE-2021-4157

Kernel crash via NFS handle overwrite

Published Mar 25, 2022 · Updated Aug 3, 2024

Out-of-bounds write in Linux Kernel NFS pNFS handling allows remote authenticated users with an NFS mount to crash systems or escalate privileges. The decode_nfs_fh function applies an incorrect size check to NFS file-handle data, permitting a one- or two-byte write beyond the destination during mirroring operations. Exploitation requires access to the NFS mount; triggering the corruption can crash the kernel and may enable privilege escalation or code execution.

CVSS severity8.0
High
EPSS probability1.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Linux Kernel NFS pNFS handling allows remote authenticated users with an NFS mount to crash systems or escalate privileges. The decode_nfs_fh function applies an incorrect size check to NFS file-handle data, permitting a one- or two-byte write beyond the destination during mirroring operations. Exploitation requires access to the NFS mount; triggering the corruption can crash the kernel and may enable privilege escalation or code execution.

The record

CVE
CVE-2021-4157
Published
Mar 25, 2022
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-119, T1068
Attack vector
adjacent
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 25, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=kernel 5.13-rc1

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=kernel 5.13-rc1

Published CVSS scores

8.0NVDCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.4NVDAV:A/AC:M/Au:S/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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