CVE-2021-47468

Service interruption via atomic-context workqueue flush

Published May 22, 2024 · Updated May 11, 2026

Improper locking in the mISDN NetJet driver in Linux allows local users to cause an availability impact during device removal. The nj_release path calls card->isac.release while holding a spin lock with interrupts disabled, and isac_release then flushes work that can sleep. Local access capable of removing the NetJet PCI driver reaches the faulty release path; public sources do not specify whether the interruption is a hang, crash, or another failure.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in the mISDN NetJet driver in Linux allows local users to cause an availability impact during device removal. The nj_release path calls card->isac.release while holding a spin lock with interrupts disabled, and isac_release then flushes work that can sleep. Local access capable of removing the NetJet PCI driver reaches the faulty release path; public sources do not specify whether the interruption is a hang, crash, or another failure.

The record

CVE
CVE-2021-47468
Published
May 22, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 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=2.6.32
  2. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <37e4f57b22cc5ebb3f80cf0f74fdeb487f082367
  3. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <4054b869dc263228d30a4755800b78f0f2ba0c89
  4. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <6510e80a0b81b5d814e3aea6297ba42f5e76f73c
  5. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <6f95c97e0f9d6eb39c3f2cb45e8fa4268d1b372b
  6. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <9f591cbdbed3d7822b2bdba89b34a6d7b434317d
  7. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <a5b34409d3fc52114c828be4adbc30744fa3258b
  8. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <ef269a8808cb1759245a98a7fe16fceaebad894c
  9. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <f5966ba53013149bcf94e1536644a958dd00a026

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.32; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <37e4f57b22cc5ebb3f80cf0f74fdeb487f082367; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <4054b869dc263228d30a4755800b78f0f2ba0c89; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <6510e80a0b81b5d814e3aea6297ba42f5e76f73c; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <6f95c97e0f9d6eb39c3f2cb45e8fa4268d1b372b; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <9f591cbdbed3d7822b2bdba89b34a6d7b434317d; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <a5b34409d3fc52114c828be4adbc30744fa3258b; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <ef269a8808cb1759245a98a7fe16fceaebad894c; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <f5966ba53013149bcf94e1536644a958dd00a026

Published CVSS scores

5.5NISTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.4OracleCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
5.5CanonicalCVSS: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 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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