CVE-2021-46959

Kernel memory corruption via stale devres classification

Published Feb 29, 2024 · Updated May 23, 2026

Use-after-free in the Linux SPI controller core allows local users to corrupt kernel memory during managed driver removal. During spi_unregister_controller(), devm_spi_release_controller() consults a devres list that cleanup has already torn down, misclassifies devm-allocated controllers as legacy objects, and decrements their reference counts below zero. Triggering the fault requires a controller created by devm_spi_alloc_master() or devm_spi_alloc_slave() and a driver-detach path that releases its managed resources.

CVSS severity7.8
High
EPSS probability0.24%
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 SPI controller core allows local users to corrupt kernel memory during managed driver removal. During spi_unregister_controller(), devm_spi_release_controller() consults a devres list that cleanup has already torn down, misclassifies devm-allocated controllers as legacy objects, and decrements their reference counts below zero. Triggering the fault requires a controller created by devm_spi_alloc_master() or devm_spi_alloc_slave() and a driver-detach path that releases its managed resources.

The record

CVE
CVE-2021-46959
Published
Feb 29, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 29, 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=0870525cf94bc27907e94ce99afb6d7239ffd2f5 <8bf96425c90f5c1dcf3b7b9df568019a1d4b8a0e
  2. Affected versionversion=234b432c7b6184b2d6c5ba2c55f0dd5023c0edf0 <28a5529068c51cdf0295ab1e11a99a3a909a03e4
  3. Affected versionversion=3e04a4976addbedcad326f47b0dd4efc570a1fac <001c8e83646ad3b847b18f6ac55a54367d917d74
  4. Affected versionversion=4.14.212 <4.14.233
  5. Affected versionversion=4.19.163 <4.19.191
  6. Affected versionversion=4.4.248 <4.4.271
  7. Affected versionversion=4.9.248 <4.9.271
  8. Affected versionversion=5.10
  9. Affected versionversion=5.4.80 <5.4.119
  10. Affected versionversion=5.9.11 <5.10
  11. Affected versionversion=5e844cc37a5cbaa460e68f9a989d321d63088a89 <794aaf01444d4e765e2b067cba01cc69c1c68ed9
  12. Affected versionversion=5e844cc37a5cbaa460e68f9a989d321d63088a89 <8735248ebb918d25427965f0db07939ed0473ec6
  13. Affected versionversion=5e844cc37a5cbaa460e68f9a989d321d63088a89 <c7fabe372a9031acd00498bc718ce27c253abfd1
  14. Affected versionversion=5e844cc37a5cbaa460e68f9a989d321d63088a89 <cee78aa24578edac8cf00513dca618c0acc17cd7
  15. Affected versionversion=8c45a1c6c951bbe7f95db78fcab46f7337364468 <8e029707f50a82c53172359c686b2536ab54e58c
  16. Affected versionversion=a4add022c1552b0d51a0b89a4781919d6ebac4f9 <62bb2c7f2411a0045c24831f11ecacfc35610815
  17. Affected versionversion=bd1a5b2307279029faaddbecf2f2ac25eaef8dc6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0870525cf94bc27907e94ce99afb6d7239ffd2f5 <8bf96425c90f5c1dcf3b7b9df568019a1d4b8a0e; version=234b432c7b6184b2d6c5ba2c55f0dd5023c0edf0 <28a5529068c51cdf0295ab1e11a99a3a909a03e4; version=3e04a4976addbedcad326f47b0dd4efc570a1fac <001c8e83646ad3b847b18f6ac55a54367d917d74; version=4.14.212 <4.14.233; version=4.19.163 <4.19.191; version=4.4.248 <4.4.271; version=4.9.248 <4.9.271; version=5.10; version=5.4.80 <5.4.119; version=5.9.11 <5.10; version=5e844cc37a5cbaa460e68f9a989d321d63088a89 <794aaf01444d4e765e2b067cba01cc69c1c68ed9; version=5e844cc37a5cbaa460e68f9a989d321d63088a89 <8735248ebb918d25427965f0db07939ed0473ec6; version=5e844cc37a5cbaa460e68f9a989d321d63088a89 <c7fabe372a9031acd00498bc718ce27c253abfd1; version=5e844cc37a5cbaa460e68f9a989d321d63088a89 <cee78aa24578edac8cf00513dca618c0acc17cd7; version=8c45a1c6c951bbe7f95db78fcab46f7337364468 <8e029707f50a82c53172359c686b2536ab54e58c; version=a4add022c1552b0d51a0b89a4781919d6ebac4f9 <62bb2c7f2411a0045c24831f11ecacfc35610815; version=bd1a5b2307279029faaddbecf2f2ac25eaef8dc6

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

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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