CVE-2021-47324Network attack vector

Kernel memory corruption via unsynchronized watchdog timer

Published May 21, 2024 · Updated May 11, 2026

Use-after-free in the Linux kernel SBC60xx watchdog driver allows attackers to corrupt kernel memory during device removal. The wdt_startup() removal path calls del_timer(), which can return while wdt_timer remains active and later accesses freed driver state. Reachability requires the SBC60xx watchdog driver and a removal race while its timer handler is running; consequences include a kernel crash or memory corruption.

CVSS severity8.8
High
EPSS probability1.16%
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 SBC60xx watchdog driver allows attackers to corrupt kernel memory during device removal. The wdt_startup() removal path calls del_timer(), which can return while wdt_timer remains active and later accesses freed driver state. Reachability requires the SBC60xx watchdog driver and a removal race while its timer handler is running; consequences include a kernel crash or memory corruption.

The record

CVE
CVE-2021-47324
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
network
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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0ac50a76cf3cd63db000648b3b19f3f98b8aaa76
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <146cc288fb80c662c9c35e7bc58325d1ac0a7875
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <63a3dc24bd053792f84cb4eef0168b1266202a02
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <862f2b5a7c38762ac9e369daefbf361a91aca685
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8adbbe6c86bb13e14f8a19e036ae5f4f5661fd90
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a397cb4576fc2fc802562418b3a50b8f67d60d31
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b4ebf4a4692e84163a69444c70ad515de06e2259
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c08a6b31e4917034f0ed0cb457c3bb209576f542
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dc9403097be52d57a5c9c35efa9be79d166a78af
  10. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <0ac50a76cf3cd63db000648b3b19f3f98b8aaa76; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <146cc288fb80c662c9c35e7bc58325d1ac0a7875; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <63a3dc24bd053792f84cb4eef0168b1266202a02; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <862f2b5a7c38762ac9e369daefbf361a91aca685; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8adbbe6c86bb13e14f8a19e036ae5f4f5661fd90; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a397cb4576fc2fc802562418b3a50b8f67d60d31; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b4ebf4a4692e84163a69444c70ad515de06e2259; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c08a6b31e4917034f0ed0cb457c3bb209576f542; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dc9403097be52d57a5c9c35efa9be79d166a78af; version=2.6.12
The Linux Kernel Organization · Linux Kernelversion=0 1da177e4c3f4 <63a3dc24bd05; version=1da177e4c3f4 <0ac50a76cf3c; version=1da177e4c3f4 <146cc288fb80; version=1da177e4c3f4 <862f2b5a7c38; version=1da177e4c3f4 <8adbbe6c86bb; version=1da177e4c3f4 <a397cb4576fc; version=1da177e4c3f4 <b4ebf4a4692e; version=1da177e4c3f4 <c08a6b31e491; version=1da177e4c3f4 <dc9403097be5

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/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)
Vectornetwork
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.

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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