CVE-2021-47284

Kernel crash via unrequested IRQ release

Published May 21, 2024 · Updated May 11, 2026

Denial of service in Linux kernel mISDN netjet code allows local users to crash the system when a NetJet device probe fails. The nj_setup failure path leaves card->irq positive before request_irq runs, so nj_release calls free_irq for an IRQ that was never requested. Reaching the fault requires the mISDN netjet driver and a failing NetJet PCI probe; with panic_on_warn enabled, the warning becomes a kernel panic.

CVSS severity4.7
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux kernel mISDN netjet code allows local users to crash the system when a NetJet device probe fails. The nj_setup failure path leaves card->irq positive before request_irq runs, so nj_release calls free_irq for an IRQ that was never requested. Reaching the fault requires the mISDN netjet driver and a failing NetJet PCI probe; with panic_on_warn enabled, the warning becomes a kernel panic.

The record

CVE
CVE-2021-47284
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-400, T1499
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=2.6.32
  2. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <143fc7220961220eecc04669e5909af8847bf8c8
  3. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <4c1fcb6ec964b44edbf84235134582a5ffae1521
  4. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <6249193e03709ea625e10706ecaf17fea0427d3d
  5. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <958cb1078ca60d214826fd90a0961a447fade59a
  6. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <9d7d4649dc1c53acf76df260fd519db698ed20d7
  7. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <9f6f852550d0e1b7735651228116ae9d300f69b3
  8. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <a0a37e4454ca1c0b424edc2c9c2487c2c46a1be6
  9. Affected versionversion=a900845e56617edc005fd8f35bfd5a407aaf96c8 <bf78e25bd3f487208e042c67c8a31706c2dba265

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.32; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <143fc7220961220eecc04669e5909af8847bf8c8; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <4c1fcb6ec964b44edbf84235134582a5ffae1521; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <6249193e03709ea625e10706ecaf17fea0427d3d; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <958cb1078ca60d214826fd90a0961a447fade59a; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <9d7d4649dc1c53acf76df260fd519db698ed20d7; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <9f6f852550d0e1b7735651228116ae9d300f69b3; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <a0a37e4454ca1c0b424edc2c9c2487c2c46a1be6; version=a900845e56617edc005fd8f35bfd5a407aaf96c8 <bf78e25bd3f487208e042c67c8a31706c2dba265
The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f4 <4c1fcb6ec964; version=1da177e4c3f4 <6249193e0370; version=1da177e4c3f4 <958cb1078ca6; version=1da177e4c3f4 <9d7d4649dc1c; version=1da177e4c3f4 <9f6f852550d0; version=1da177e4c3f4 <a0a37e4454ca; version=1da177e4c3f4 <bf78e25bd3f4; version=da177e4c3f4 <143fc7220961

Published CVSS scores

4.7CISA-ADPCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5OracleCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5SUSECVSS: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-400Uncontrolled Resource Consumption
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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