CVE-2021-47302

Kernel memory corruption via stale TX descriptor

Published May 21, 2024 · Updated May 11, 2026

Use-after-free in the Linux kernel igc driver allows local users to corrupt kernel memory during a concurrent controller reset. The igc TX-ring cleanup path leaves next_to_watch pointing at an already freed socket buffer, so concurrent igc_poll() processing frees the buffer again. Triggering the race requires local low-privileged access, an active igc network device, and overlap between polling and controller reset; the observed result is a kernel refcount underflow and invalid memory access.

CVSS severity7.8
High
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

Use-after-free in the Linux kernel igc driver allows local users to corrupt kernel memory during a concurrent controller reset. The igc TX-ring cleanup path leaves next_to_watch pointing at an already freed socket buffer, so concurrent igc_poll() processing frees the buffer again. Triggering the race requires local low-privileged access, an active igc network device, and overlap between polling and controller reset; the observed result is a kernel refcount underflow and invalid memory access.

The record

CVE
CVE-2021-47302
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 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=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <56ea7ed103b46970e171eb1c95916f393d64eeff
  2. Affected versionversion=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <a9508e0edfe369ac95d0825bcdca976436ce780f
  3. Affected versionversion=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <e15f629036bac005fc758b4ad17896cf2312add4
  4. Affected versionversion=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <ea5e36b7367ea0a36ef73a163768f16d2977bd83
  5. Affected versionversion=4.20

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <56ea7ed103b46970e171eb1c95916f393d64eeff; version=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <a9508e0edfe369ac95d0825bcdca976436ce780f; version=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <e15f629036bac005fc758b4ad17896cf2312add4; version=13b5b7fd6a4a96dffe604f25e7b64cfbd9520924 <ea5e36b7367ea0a36ef73a163768f16d2977bd83; version=4.20

Published CVSS scores

6.4SUSECVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
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

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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-416Use After Free
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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