CVE-2021-47459

Kernel memory corruption via J1939 reference race

Published May 22, 2024 · Updated Aug 5, 2026

Use-after-free in the Linux kernel J1939 CAN stack allows local users to corrupt kernel memory by racing socket bind operations. In j1939_netdev_start(), concurrent bind paths can decrement rx_kref to zero and then increment the freed j1939_priv because kref_get() and kref_put() lack the shared j1939_netdev_lock. Exploitation requires concurrent J1939 socket binds against one CAN device; the published trace establishes a refcount warning and use-after-free, not a specific privilege gain.

CVSS severity7.8
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel J1939 CAN stack allows local users to corrupt kernel memory by racing socket bind operations. In j1939_netdev_start(), concurrent bind paths can decrement rx_kref to zero and then increment the freed j1939_priv because kref_get() and kref_put() lack the shared j1939_netdev_lock. Exploitation requires concurrent J1939 socket binds against one CAN device; the published trace establishes a refcount warning and use-after-free, not a specific privilege gain.

The record

CVE
CVE-2021-47459
Published
May 22, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 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=5.4
  2. Affected versionversion=9d71dd0c70099914fcd063135da3c580865e924c <6e8811707e2df0c6ba920f0cad3a3bca7b42132f
  3. Affected versionversion=9d71dd0c70099914fcd063135da3c580865e924c <864e77771a24c877aaf53aee019f78619cbcd668
  4. Affected versionversion=9d71dd0c70099914fcd063135da3c580865e924c <a0e47d2833b4f65e6c799f28c6b636d36b8b936d
  5. Affected versionversion=9d71dd0c70099914fcd063135da3c580865e924c <d9d52a3ebd284882f5562c88e55991add5d01586

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.4; version=9d71dd0c70099914fcd063135da3c580865e924c <6e8811707e2df0c6ba920f0cad3a3bca7b42132f; version=9d71dd0c70099914fcd063135da3c580865e924c <864e77771a24c877aaf53aee019f78619cbcd668; version=9d71dd0c70099914fcd063135da3c580865e924c <a0e47d2833b4f65e6c799f28c6b636d36b8b936d; version=9d71dd0c70099914fcd063135da3c580865e924c <d9d52a3ebd284882f5562c88e55991add5d01586

Published CVSS scores

7.8NIST NVDCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

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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