CVE-2021-47476

Kernel crash via undersized USB endpoint buffers

Published May 22, 2024 · Updated May 11, 2026

NULL pointer dereference in the Linux ni_usb6501 driver allows physically proximate attackers to crash the kernel via a malicious USB device. The probe path trusts undersized endpoint maximum-packet values, so ni6501_port_command() and ni6501_counter_command() allocate zero-length or insufficient USB transfer buffers and then dereference or overflow them. Exploitation requires attaching a crafted USB device; successful triggering interrupts the affected host rather than exposing or modifying data.

CVSS severity4.6
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

NULL pointer dereference in the Linux ni_usb6501 driver allows physically proximate attackers to crash the kernel via a malicious USB device. The probe path trusts undersized endpoint maximum-packet values, so ni6501_port_command() and ni6501_counter_command() allocate zero-length or insufficient USB transfer buffers and then dereference or overflow them. Exploitation requires attaching a crafted USB device; successful triggering interrupts the affected host rather than exposing or modifying data.

The record

CVE
CVE-2021-47476
Published
May 22, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1200
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.18
  2. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <4a9d43cb5d5f39fa39fc1da438517004cc95f7ea
  3. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <58478143771b20ab219937b1c30a706590a59224
  4. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <907767da8f3a925b060c740e0b5c92ea7dbec440
  5. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <aa39738423503825625853b643b9e99d11c23816
  6. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <b0156b7c9649d8f55a2ce3d3258509f1b2a181c3
  7. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <bc51111bf6e8e7b6cc94b133e4c291273a16acd1
  8. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <d6a727a681a39ae4f73081a9bedb45d14f95bdd1
  9. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <df7b1238f3b599a0b9284249772cdfd1ea83a632
  10. Affected versionversion=a03bb00e50ab4c07107da58a52a0bff7943f360c <ef143dc0c3defe56730ecd3a9de7b3e1d7e557c1

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.18; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <4a9d43cb5d5f39fa39fc1da438517004cc95f7ea; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <58478143771b20ab219937b1c30a706590a59224; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <907767da8f3a925b060c740e0b5c92ea7dbec440; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <aa39738423503825625853b643b9e99d11c23816; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <b0156b7c9649d8f55a2ce3d3258509f1b2a181c3; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <bc51111bf6e8e7b6cc94b133e4c291273a16acd1; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <d6a727a681a39ae4f73081a9bedb45d14f95bdd1; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <df7b1238f3b599a0b9284249772cdfd1ea83a632; version=a03bb00e50ab4c07107da58a52a0bff7943f360c <ef143dc0c3defe56730ecd3a9de7b3e1d7e557c1

Published CVSS scores

4.6CISA-ADPCVSS:3.1/AV:P/AC:L/PR:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1200Hardware Additions

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo