CVE-2021-47507

Kernel crash via nfsd registration race

Published May 24, 2024 · Updated May 23, 2026

Race condition in Linux kernel nfsd affected releases allows local users to crash the kernel while mounting the RPC pipe filesystem. register_cld_notifier() can expose rpc_pipefs_event() before register_pernet_subsys() registers nfsd_net_id, so the callback dereferences unavailable per-network data. Local low-privileged access and successful race timing are required, and a trigger interrupts the host through a NULL-pointer kernel fault.

CVSS severity4.7
Medium
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 Linux kernel nfsd affected releases allows local users to crash the kernel while mounting the RPC pipe filesystem. register_cld_notifier() can expose rpc_pipefs_event() before register_pernet_subsys() registers nfsd_net_id, so the callback dereferences unavailable per-network data. Local low-privileged access and successful race timing are required, and a trigger interrupts the host through a NULL-pointer kernel fault.

The record

CVE
CVE-2021-47507
Published
May 24, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 2024CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=4d41f65efeec0a6da6088341203c81e49ebfcd90
  2. Affected versionversion=5.10.20 <5.10.85
  3. Affected versionversion=5.11.3 <5.12
  4. Affected versionversion=5.12
  5. Affected versionversion=5.4.102 <5.4.165
  6. Affected versionversion=7c7cb07d4affcf41749234fe9dc4d90cd3959e32 <c520943a00ad5015704969ad3304c956bcd49d25
  7. Affected versionversion=8677e99150b0830d29cc1318b4cc559e176940bb <f5734b1714ca355703e9ea8fb61d04beff1790b9
  8. Affected versionversion=bd5ae9288d6451bd346a1b4a59d4fe7e62ba29b7 <8bf902fee5893cfc2f04a698abab47629699ae9a
  9. Affected versionversion=bd5ae9288d6451bd346a1b4a59d4fe7e62ba29b7 <b10252c7ae9c9d7c90552f88b544a44ee773af64

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4d41f65efeec0a6da6088341203c81e49ebfcd90; version=5.10.20 <5.10.85; version=5.11.3 <5.12; version=5.12; version=5.4.102 <5.4.165; version=7c7cb07d4affcf41749234fe9dc4d90cd3959e32 <c520943a00ad5015704969ad3304c956bcd49d25; version=8677e99150b0830d29cc1318b4cc559e176940bb <f5734b1714ca355703e9ea8fb61d04beff1790b9; version=bd5ae9288d6451bd346a1b4a59d4fe7e62ba29b7 <8bf902fee5893cfc2f04a698abab47629699ae9a; version=bd5ae9288d6451bd346a1b4a59d4fe7e62ba29b7 <b10252c7ae9c9d7c90552f88b544a44ee773af64

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7UbuntuCVSS:3.1/AV:L/AC:H/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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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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