CVE-2021-46966

Kernel crash via freed ACPI method buffer

Published Feb 27, 2024 · Updated May 23, 2026

Use-after-free in affected Linux kernel releases allows local users to trigger invalid memory access through repeated ACPI custom-method writes. In drivers/acpi/custom_method.c, cm_write() frees its persistent buffer after a short write but retains the pointer, so a later call reuses freed memory. Access requires permission to write the custom_method debugfs interface; the resulting kernel-memory corruption can crash the host.

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 affected Linux kernel releases allows local users to trigger invalid memory access through repeated ACPI custom-method writes. In drivers/acpi/custom_method.c, cm_write() frees its persistent buffer after a short write but retains the pointer, so a later call reuses freed memory. Access requires permission to write the custom_method debugfs interface; the resulting kernel-memory corruption can crash the host.

The record

CVE
CVE-2021-46966
Published
Feb 27, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2024CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=03d1571d9513369c17e6848476763ebbd10ec2cb <62dc2440ebb552aa0d7f635e1697e077d9d21203
  2. Affected versionversion=03d1571d9513369c17e6848476763ebbd10ec2cb <72814a94c38a33239793f7622cec6ace1e540c4b
  3. Affected versionversion=03d1571d9513369c17e6848476763ebbd10ec2cb <b7a5baaae212a686ceb812c32fceed79c03c0234
  4. Affected versionversion=03d1571d9513369c17e6848476763ebbd10ec2cb <e483bb9a991bdae29a0caa4b3a6d002c968f94aa
  5. Affected versionversion=03d1571d9513369c17e6848476763ebbd10ec2cb <f16737caf41fc06cfe6e49048becb09657074d4b
  6. Affected versionversion=06cd4a06eb596a888239fb8ceb6ea15677cab396
  7. Affected versionversion=35b88a10535edcf62d3e6b7893a8cd506ff98a24 <90575d1d9311b753cf1718f4ce9061ddda7dfd23
  8. Affected versionversion=4.14.147 <4.14.233
  9. Affected versionversion=4.19.77 <4.19.191
  10. Affected versionversion=4.4.195 <4.4.269
  11. Affected versionversion=4.9.195 <4.9.269
  12. Affected versionversion=4bda2b79a9d04c8ba31681c66e95877dbb433416 <1d53ca5d131074c925ce38361fb0376d3bf7e394
  13. Affected versionversion=5.2.19 <5.3
  14. Affected versionversion=5.3.4 <5.4
  15. Affected versionversion=5.4
  16. Affected versionversion=5c12dadcbef8cd55ef1f5dac799bfcbb7ea7db1d <8b04d57f30caf76649d0567551589af9a66ca9be
  17. Affected versionversion=70424999fbf1f160ade111cb9baab51776e0f9c2
  18. Affected versionversion=e4467fb6ef547aa352dc03397f9474ec84eced5b <a5b26a2e362f572d87e9fd35435680e557052a17

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=03d1571d9513369c17e6848476763ebbd10ec2cb <62dc2440ebb552aa0d7f635e1697e077d9d21203; version=03d1571d9513369c17e6848476763ebbd10ec2cb <72814a94c38a33239793f7622cec6ace1e540c4b; version=03d1571d9513369c17e6848476763ebbd10ec2cb <b7a5baaae212a686ceb812c32fceed79c03c0234; version=03d1571d9513369c17e6848476763ebbd10ec2cb <e483bb9a991bdae29a0caa4b3a6d002c968f94aa; version=03d1571d9513369c17e6848476763ebbd10ec2cb <f16737caf41fc06cfe6e49048becb09657074d4b; version=06cd4a06eb596a888239fb8ceb6ea15677cab396; version=35b88a10535edcf62d3e6b7893a8cd506ff98a24 <90575d1d9311b753cf1718f4ce9061ddda7dfd23; version=4.14.147 <4.14.233; version=4.19.77 <4.19.191; version=4.4.195 <4.4.269; version=4.9.195 <4.9.269; version=4bda2b79a9d04c8ba31681c66e95877dbb433416 <1d53ca5d131074c925ce38361fb0376d3bf7e394; version=5.2.19 <5.3; version=5.3.4 <5.4; version=5.4; version=5c12dadcbef8cd55ef1f5dac799bfcbb7ea7db1d <8b04d57f30caf76649d0567551589af9a66ca9be; version=70424999fbf1f160ade111cb9baab51776e0f9c2; version=e4467fb6ef547aa352dc03397f9474ec84eced5b <a5b26a2e362f572d87e9fd35435680e557052a17

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

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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