CVE-2021-47547

Local kernel data corruption via full PHY array

Published May 24, 2024 · Updated May 11, 2026

Out-of-bounds access in the Linux kernel de4x5 Ethernet driver allows local users to alter kernel data or interrupt service. During generic MII discovery, mii_get_phy lets k reach eight after scanning a full lp->phy array, then writes address, identifier, and speed-control fields through the invalid slot. Reachability requires the de4x5 driver and a device state in which all eight PHY records already have nonzero identifiers.

CVSS severity4.4
Medium
EPSS probability0.23%
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 access in the Linux kernel de4x5 Ethernet driver allows local users to alter kernel data or interrupt service. During generic MII discovery, mii_get_phy lets k reach eight after scanning a full lp->phy array, then writes address, identifier, and speed-control fields through the invalid slot. Reachability requires the de4x5 driver and a device state in which all eight PHY records already have nonzero identifiers.

The record

CVE
CVE-2021-47547
Published
May 24, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-129
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 24, 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?

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  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <12f907cb11576b8cd0b1d95a16d1f10ed5bb7237
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <142ead3dc70411bd5977e8c47a6d8bf22287b3f8
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2c1a6a9a011d622a7c61324a97a49801ba425eff
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <61217be886b5f7402843677e4be7e7e83de9cb41
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <77ff166909458646e66450e42909e0adacc99049
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d3dedaa5a601107cfedda087209772c76e364d58
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ec5bd0aef1cec96830d0c7e06d3597d9e786cc98
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f059fa40f0fcc6bc7a12e0f2a2504e9a4ff74f1f
  9. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <12f907cb11576b8cd0b1d95a16d1f10ed5bb7237; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <142ead3dc70411bd5977e8c47a6d8bf22287b3f8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2c1a6a9a011d622a7c61324a97a49801ba425eff; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <61217be886b5f7402843677e4be7e7e83de9cb41; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <77ff166909458646e66450e42909e0adacc99049; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d3dedaa5a601107cfedda087209772c76e364d58; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ec5bd0aef1cec96830d0c7e06d3597d9e786cc98; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f059fa40f0fcc6bc7a12e0f2a2504e9a4ff74f1f; version=2.6.12

Published CVSS scores

4.4CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

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-129Improper Validation of Array Index

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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