CVE-2021-47386

System crash via w83791d NULL pointer dereference

Published May 21, 2024 · Updated May 11, 2026

NULL pointer dereference in the Linux kernel w83791d driver allows local users to crash the system through a qualifying device-register value. The driver evaluates that value and dereferences an obsolete lm75[] entry after subclient creation moved to devm_i2c_new_dummy_device(). Reachability requires the w83791d driver and compatible hardware; no data access or code execution is documented.

CVSS severity7.8
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel w83791d driver allows local users to crash the system through a qualifying device-register value. The driver evaluates that value and dereferences an obsolete lm75[] entry after subclient creation moved to devm_i2c_new_dummy_device(). Reachability requires the w83791d driver and compatible hardware; no data access or code execution is documented.

The record

CVE
CVE-2021-47386
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <16887ae4e3defd2c4e7913b6c539f33eaf4eac5c
  2. Affected versionversion=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <44d3c480e4e2a75bf6296a18b4356157991ccd80
  3. Affected versionversion=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <516d9055039017a20a698103be2b556b4c976bb8
  4. Affected versionversion=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <943c15ac1b84d378da26bba41c83c67e16499ac4
  5. Affected versionversion=5.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <16887ae4e3defd2c4e7913b6c539f33eaf4eac5c; version=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <44d3c480e4e2a75bf6296a18b4356157991ccd80; version=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <516d9055039017a20a698103be2b556b4c976bb8; version=358d2071100d84cfe6ef4a9d70ac0d998a1d501e <943c15ac1b84d378da26bba41c83c67e16499ac4; version=5.4

Published CVSS scores

4.4Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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