CVE-2021-47578

Kernel crash via zero-size scsi_debug allocation

Published Jun 19, 2024 · Updated May 11, 2026

NULL pointer dereference in Linux 5.8 through 5.10.87 and 5.11 through 5.15.10 allows local users to crash the kernel via scsi_debug. drivers/scsi/scsi_debug.c calls kcalloc() with a zero element count, receives ZERO_SIZE_PTR rather than NULL, and later passes that invalid pointer to sg_copy_buffer(), which writes through memcpy(). Reaching the fault requires local access to issue SCSI commands to a scsi_debug virtual device; the demonstrated consequence is a kernel crash, with no reported confidentiality or integrity impact.

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 Linux 5.8 through 5.10.87 and 5.11 through 5.15.10 allows local users to crash the kernel via scsi_debug. drivers/scsi/scsi_debug.c calls kcalloc() with a zero element count, receives ZERO_SIZE_PTR rather than NULL, and later passes that invalid pointer to sg_copy_buffer(), which writes through memcpy(). Reaching the fault requires local access to issue SCSI commands to a scsi_debug virtual device; the demonstrated consequence is a kernel crash, with no reported confidentiality or integrity impact.

The record

CVE
CVE-2021-47578
Published
Jun 19, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 19, 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=5.8
  2. Affected versionversion=c3e2fe9222d428f115baeba2f6b3637b3aa444cd <3344b58b53a76199dae48faa396e9fc37bf86992
  3. Affected versionversion=c3e2fe9222d428f115baeba2f6b3637b3aa444cd <47d11d35203b0aa13533634e270fe2c3610e531b
  4. Affected versionversion=c3e2fe9222d428f115baeba2f6b3637b3aa444cd <aa1f912712a109b6306746133de7e5343f016b26

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.8; version=c3e2fe9222d428f115baeba2f6b3637b3aa444cd <3344b58b53a76199dae48faa396e9fc37bf86992; version=c3e2fe9222d428f115baeba2f6b3637b3aa444cd <47d11d35203b0aa13533634e270fe2c3610e531b; version=c3e2fe9222d428f115baeba2f6b3637b3aa444cd <aa1f912712a109b6306746133de7e5343f016b26

Published CVSS scores

5.5NIST NVDCVSS: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

CWE-476NULL Pointer Dereference
T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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