CVE-2021-47337

Kernel crash via invalid error-handler pointer dereference

Published May 21, 2024 · Updated May 23, 2026

NULL pointer dereference in the Linux kernel SCSI core in affected releases allows local users to crash the kernel during SCSI host cleanup. When error-handler thread creation fails, scsi_host_alloc leaves shost->ehandler as an ERR_PTR value, and scsi_host_dev_release passes it to kthread_stop because it checks only for NULL. The failure path requires local low-privileged access and a SCSI host allocation whose error-handler thread cannot start; the invalid read produces a kernel oops and service interruption.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in the Linux kernel SCSI core in affected releases allows local users to crash the kernel during SCSI host cleanup. When error-handler thread creation fails, scsi_host_alloc leaves shost->ehandler as an ERR_PTR value, and scsi_host_dev_release passes it to kthread_stop because it checks only for NULL. The failure path requires local low-privileged access and a SCSI host allocation whose error-handler thread cannot start; the invalid read produces a kernel oops and service interruption.

The record

CVE
CVE-2021-47337
Published
May 21, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=2dc85045ae65b9302a1d2e2ddd7ce4c030153a6a <e1bd3fac2baa3d5c04375980c1d5263a3335af92
  2. Affected versionversion=4.14.237 <4.14.240
  3. Affected versionversion=4.19.195 <4.19.198
  4. Affected versionversion=45d83db4728127944b237c0c8248987df9d478e7 <8e4212ecf0713dd57d0e3209a66201da582149b1
  5. Affected versionversion=4.9.273 <4.9.276
  6. Affected versionversion=5.10.44 <5.10.52
  7. Affected versionversion=5.12.11 <5.12.19
  8. Affected versionversion=5.13
  9. Affected versionversion=5.4.126 <5.4.134
  10. Affected versionversion=66a834d092930cf41d809c0e989b13cd6f9ca006 <93aa71ad7379900e61c8adff6a710a4c18c7c99b
  11. Affected versionversion=66a834d092930cf41d809c0e989b13cd6f9ca006 <c1671d2d2ef8a84837eea1b4d99ca0c6a66fb691
  12. Affected versionversion=79296e292d67fa7b5fb8d8c27343683e823872c8 <887bfae2732b5b02a86a859fd239d34f7ff93c05
  13. Affected versionversion=7a696ce1d5d16a33a6cd6400bbcc0339b2460e11 <ea518b70ed5e4598c8d706f37fc16f7b06e440bd
  14. Affected versionversion=8958181c1663e24a13434448e7d6b96b5d04900a <d2f0b960d07e52bb664471b4de0ed8b08c636b3a
  15. Affected versionversion=db08ce595dd64ea9859f7d088b51cbfc8e685c66 <f3d0a109240c9bed5c60d819014786be3a2fe515

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2dc85045ae65b9302a1d2e2ddd7ce4c030153a6a <e1bd3fac2baa3d5c04375980c1d5263a3335af92; version=4.14.237 <4.14.240; version=4.19.195 <4.19.198; version=45d83db4728127944b237c0c8248987df9d478e7 <8e4212ecf0713dd57d0e3209a66201da582149b1; version=4.9.273 <4.9.276; version=5.10.44 <5.10.52; version=5.12.11 <5.12.19; version=5.13; version=5.4.126 <5.4.134; version=66a834d092930cf41d809c0e989b13cd6f9ca006 <93aa71ad7379900e61c8adff6a710a4c18c7c99b; version=66a834d092930cf41d809c0e989b13cd6f9ca006 <c1671d2d2ef8a84837eea1b4d99ca0c6a66fb691; version=79296e292d67fa7b5fb8d8c27343683e823872c8 <887bfae2732b5b02a86a859fd239d34f7ff93c05; version=7a696ce1d5d16a33a6cd6400bbcc0339b2460e11 <ea518b70ed5e4598c8d706f37fc16f7b06e440bd; version=8958181c1663e24a13434448e7d6b96b5d04900a <d2f0b960d07e52bb664471b4de0ed8b08c636b3a; version=db08ce595dd64ea9859f7d088b51cbfc8e685c66 <f3d0a109240c9bed5c60d819014786be3a2fe515

Published CVSS scores

5.5NIST National Vulnerability DatabaseCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7SUSECVSS: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-476NULL Pointer Dereference
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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