CVE-2021-47006

Local service interruption via missed breakpoint single-stepping

Published Feb 28, 2024 · Updated May 11, 2026

Improper handler validation in Linux kernel 4.7 through 5.12.4 allows local users to interrupt service through an ARM hardware breakpoint. The ARM hw_breakpoint path tests whether overflow_handler is null even though perf_event_alloc assigns a default handler, so enable_single_step is never called. Exploitation requires low-privileged local access on an affected ARM system, and the published impact is limited to availability.

CVSS severity5.5
Medium
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper handler validation in Linux kernel 4.7 through 5.12.4 allows local users to interrupt service through an ARM hardware breakpoint. The ARM hw_breakpoint path tests whether overflow_handler is null even though perf_event_alloc assigns a default handler, so enable_single_step is never called. Exploitation requires low-privileged local access on an affected ARM system, and the published impact is limited to availability.

The record

CVE
CVE-2021-47006
Published
Feb 28, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
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=1879445dfa7bbd6fe21b09c5cc72f4934798afed <3ed8832aeaa9a37b0fc386bb72ff604352567c80
  2. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <555a70f7fff03bd669123487905c47ae27dbdaac
  3. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <630146203108bf6b8934eec0dfdb3e46dcb917de
  4. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <7eeacc6728c5478e3c01bc82a1f08958eaa12366
  5. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <a506bd5756290821a4314f502b4bafc2afcf5260
  6. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <a9938d6d78a238d6ab8de57a4d3dcf77adceb9bb
  7. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <dabe299425b1a53a69461fed7ac8922ea6733a25
  8. Affected versionversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <ed1f67465327cec4457bb988775245b199da86e6
  9. Affected versionversion=4.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1879445dfa7bbd6fe21b09c5cc72f4934798afed <3ed8832aeaa9a37b0fc386bb72ff604352567c80; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <555a70f7fff03bd669123487905c47ae27dbdaac; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <630146203108bf6b8934eec0dfdb3e46dcb917de; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <7eeacc6728c5478e3c01bc82a1f08958eaa12366; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <a506bd5756290821a4314f502b4bafc2afcf5260; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <a9938d6d78a238d6ab8de57a4d3dcf77adceb9bb; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <dabe299425b1a53a69461fed7ac8922ea6733a25; version=1879445dfa7bbd6fe21b09c5cc72f4934798afed <ed1f67465327cec4457bb988775245b199da86e6; version=4.7

Published CVSS scores

5.5CISA ADPCVSS: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

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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