CVE-2021-47168Network attack vector

Memory corruption via oversized NFS file handle

Published Mar 25, 2024 · Updated Aug 5, 2026

Out-of-bounds write in the Linux kernel NFS file-layout decoder since 2.6.37 allows remote attackers to corrupt memory via a layout response. filelayout_decode_layout() gives nfs_fh_from_wire() sizeof(struct nfs_fh) as the limit for a smaller NFS_MAXFHSIZE data buffer, permitting a two-byte overwrite. Reachability requires a Linux NFS client to process pNFS files-layout metadata; the published record establishes memory corruption but not code execution.

CVSS severity9.8
Critical
EPSS probability0.76%
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 the Linux kernel NFS file-layout decoder since 2.6.37 allows remote attackers to corrupt memory via a layout response. filelayout_decode_layout() gives nfs_fh_from_wire() sizeof(struct nfs_fh) as the limit for a smaller NFS_MAXFHSIZE data buffer, permitting a two-byte overwrite. Reachability requires a Linux NFS client to process pNFS files-layout metadata; the published record establishes memory corruption but not code execution.

The record

CVE
CVE-2021-47168
Published
Mar 25, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 25, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record 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=16b374ca439fb406e46e071f75428f5b033056f8 <769b01ea68b6c49dc3cde6adf7e53927dacbd3a8
  2. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <945ebef997227ca8c20bad7f8a8358c8ee57a84a
  3. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <9b367fe770b1b80d7bf64ed0d177544a44405f6e
  4. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <9d280ab53df1d4a1043bd7a9e7c6a2f9cfbfe040
  5. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <b287521e9e94bb342ebe5fd8c3fd7db9aef4e6f1
  6. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <d34fb628f6ef522f996205a9e578216bbee09e84
  7. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <e411df81cd862ef3d5b878120b2a2fef0ca9cdb1
  8. Affected versionversion=16b374ca439fb406e46e071f75428f5b033056f8 <f299522eda1566cbfbae4b15c82970fc41b03714
  9. Affected versionversion=2.6.37

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=16b374ca439fb406e46e071f75428f5b033056f8 <769b01ea68b6c49dc3cde6adf7e53927dacbd3a8; version=16b374ca439fb406e46e071f75428f5b033056f8 <945ebef997227ca8c20bad7f8a8358c8ee57a84a; version=16b374ca439fb406e46e071f75428f5b033056f8 <9b367fe770b1b80d7bf64ed0d177544a44405f6e; version=16b374ca439fb406e46e071f75428f5b033056f8 <9d280ab53df1d4a1043bd7a9e7c6a2f9cfbfe040; version=16b374ca439fb406e46e071f75428f5b033056f8 <b287521e9e94bb342ebe5fd8c3fd7db9aef4e6f1; version=16b374ca439fb406e46e071f75428f5b033056f8 <d34fb628f6ef522f996205a9e578216bbee09e84; version=16b374ca439fb406e46e071f75428f5b033056f8 <e411df81cd862ef3d5b878120b2a2fef0ca9cdb1; version=16b374ca439fb406e46e071f75428f5b033056f8 <f299522eda1566cbfbae4b15c82970fc41b03714; version=2.6.37

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

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No observations available

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

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

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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