CVE-2021-47475

Kernel memory corruption via undersized USB buffers

Published May 22, 2024 · Updated May 11, 2026

Out-of-bounds writes in the Linux kernel vmk80xx Comedi USB driver allow physically proximate attackers to corrupt kernel memory. The driver allocates transfer buffers from untrusted USB endpoint packet sizes, then accesses fixed offsets such as byte 18 without ensuring that the allocation is large enough. Exploitation requires a crafted USB device to be attached and handled by the vmk80xx driver, causing writes beyond the allocated kernel buffer.

CVSS severity7.8
High
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds writes in the Linux kernel vmk80xx Comedi USB driver allow physically proximate attackers to corrupt kernel memory. The driver allocates transfer buffers from untrusted USB endpoint packet sizes, then accesses fixed offsets such as byte 18 without ensuring that the allocation is large enough. Exploitation requires a crafted USB device to be attached and handled by the vmk80xx driver, causing writes beyond the allocated kernel buffer.

The record

CVE
CVE-2021-47475
Published
May 22, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787, 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

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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=2.6.31
  2. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <06ac746d57e6d32b062e220415c607b7e2e0fa50
  3. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <199acd8c110e3ae62833c24f632b0bb1c9f012a9
  4. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <278484ae93297b1bb1ce755f9d3b6d95a48c7d47
  5. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <33d7a470730dfe7c9bfc8da84575cf2cedd60d00
  6. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <40d2a7e278e2e7c0a5fd7e997e7eb63945bf93f7
  7. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <5229159f1d052821007aff1a1beb7873eacf1a9f
  8. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <7a2021b896de1ad559d33b5c5cdd20b982242088
  9. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <a23461c47482fc232ffc9b819539d1f837adf2b1
  10. Affected versionversion=985cafccbf9b7f862aa1c5ee566801e18b5161fb <ec85bcff4ed09260243d8f39faba99e1041718ba

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.31; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <06ac746d57e6d32b062e220415c607b7e2e0fa50; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <199acd8c110e3ae62833c24f632b0bb1c9f012a9; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <278484ae93297b1bb1ce755f9d3b6d95a48c7d47; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <33d7a470730dfe7c9bfc8da84575cf2cedd60d00; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <40d2a7e278e2e7c0a5fd7e997e7eb63945bf93f7; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <5229159f1d052821007aff1a1beb7873eacf1a9f; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <7a2021b896de1ad559d33b5c5cdd20b982242088; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <a23461c47482fc232ffc9b819539d1f837adf2b1; version=985cafccbf9b7f862aa1c5ee566801e18b5161fb <ec85bcff4ed09260243d8f39faba99e1041718ba

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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

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Your stack

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