CVE-2021-47163

Kernel crash via deferred TIPC cleanup race

Published Mar 25, 2024 · Updated Aug 5, 2026

Race condition in the TIPC UDP bearer teardown in Linux allows local users with module-control privileges to crash the kernel. During TIPC module removal, sock_release() is deferred to a work queue; cleanup_beareri() can then run after its module code has been unloaded. Reaching the race requires privilege to load, configure, and unload the TIPC module repeatedly, and successful exploitation interrupts the host through a kernel crash.

CVSS severity7.8
High
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the TIPC UDP bearer teardown in Linux allows local users with module-control privileges to crash the kernel. During TIPC module removal, sock_release() is deferred to a work queue; cleanup_beareri() can then run after its module code has been unloaded. Reaching the race requires privilege to load, configure, and unload the TIPC module repeatedly, and successful exploitation interrupts the host through a kernel crash.

The record

CVE
CVE-2021-47163
Published
Mar 25, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
local
Privileges
authenticated

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=4.1
  2. Affected versionversion=d0f91938bede204a343473792529e0db7d599836 <04c26faa51d1e2fe71cf13c45791f5174c37f986
  3. Affected versionversion=d0f91938bede204a343473792529e0db7d599836 <5195ec5e365a2a9331bfeb585b613a6e94f98dba
  4. Affected versionversion=d0f91938bede204a343473792529e0db7d599836 <b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d
  5. Affected versionversion=d0f91938bede204a343473792529e0db7d599836 <d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.1; version=d0f91938bede204a343473792529e0db7d599836 <04c26faa51d1e2fe71cf13c45791f5174c37f986; version=d0f91938bede204a343473792529e0db7d599836 <5195ec5e365a2a9331bfeb585b613a6e94f98dba; version=d0f91938bede204a343473792529e0db7d599836 <b9f5b7ad4ac3af006443f535b1ce7bff1d130d7d; version=d0f91938bede204a343473792529e0db7d599836 <d1f76dfadaf8f47ed1753f97dbcbd41c16215ffa

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8kernel.orgCVSS: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-667Improper Locking
T1499Endpoint Denial of Service

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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