CVE-2021-46994

Local system crash via uninitialized restart workqueue

Published Feb 28, 2024 · Updated May 11, 2026

NULL pointer dereference in the Linux kernel mcp251x CAN driver allows local users to crash the system during resume after suspend. The resume path queues priv->restart_work although its workqueue is initialized only by mcp251x_open(), which has not run when the interface was never enabled. The host must use the mcp251x driver and undergo suspend and resume before that CAN interface is opened; the bounded consequence is a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.24%
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 mcp251x CAN driver allows local users to crash the system during resume after suspend. The resume path queues priv->restart_work although its workqueue is initialized only by mcp251x_open(), which has not run when the interface was never enabled. The host must use the mcp251x driver and undergo suspend and resume before that CAN interface is opened; the bounded consequence is a kernel crash.

The record

CVE
CVE-2021-46994
Published
Feb 28, 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. Feb 28, 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=5.5
  2. Affected versionversion=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <03c427147b2d3e503af258711af4fc792b89b0af
  3. Affected versionversion=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <6f8f1c27b577de15f69fefce3c502bb6300d825c
  4. Affected versionversion=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <e1e10a390fd9479209c4d834d916ca5e6d5d396b
  5. Affected versionversion=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <eecb4df8ec9f896b19ee05bfa632ac6c1dcd8f21

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.5; version=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <03c427147b2d3e503af258711af4fc792b89b0af; version=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <6f8f1c27b577de15f69fefce3c502bb6300d825c; version=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <e1e10a390fd9479209c4d834d916ca5e6d5d396b; version=8ce8c0abcba314e1fe954a1840f6568bf5aef2ef <eecb4df8ec9f896b19ee05bfa632ac6c1dcd8f21

Published CVSS scores

5.5UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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-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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