CVE-2021-47357

Kernel memory corruption via unsynchronized timer deletion

Published May 21, 2024 · Updated May 11, 2026

Use-after-free in the Linux iphase ATM driver allows local users to corrupt kernel memory by unloading the module during timer execution. The ia_module_exit() removal path calls del_timer(), which does not wait for the timer handler to finish before the driver's remove function returns. Triggering requires module removal while the timer handler is active; the dangling handler can access freed kernel memory and crash the system.

CVSS severity7.8
High
EPSS probability0.25%
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 iphase ATM driver allows local users to corrupt kernel memory by unloading the module during timer execution. The ia_module_exit() removal path calls del_timer(), which does not wait for the timer handler to finish before the driver's remove function returns. Triggering requires module removal while the timer handler is active; the dangling handler can access freed kernel memory and crash the system.

The record

CVE
CVE-2021-47357
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
Unavailable

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 <1c72e6ab66b9598cac741ed397438a52065a8f1f
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <89ce0b0747f319eb70f85bc820dcc43cebbd5417
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9e161687855175334ca93c6c3ccb221731194479
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a832ee2f2145f57443b2d565f8cb5490e8339f42
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b58d246a058ae88484758cd4ab27b3180fd5ecf8
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bcdd2be48edd8c6867fb44112cb8d18086beae29
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c9172498d4d62c9b64e5fb37c1ee0343e65fe51b
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d1fb12412874c94ad037e11d0ecdd1140a439297
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e759ff76ebbbfcdcf83b6634c54dc47828573d8b
  10. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1c72e6ab66b9598cac741ed397438a52065a8f1f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <89ce0b0747f319eb70f85bc820dcc43cebbd5417; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <9e161687855175334ca93c6c3ccb221731194479; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a832ee2f2145f57443b2d565f8cb5490e8339f42; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b58d246a058ae88484758cd4ab27b3180fd5ecf8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bcdd2be48edd8c6867fb44112cb8d18086beae29; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c9172498d4d62c9b64e5fb37c1ee0343e65fe51b; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d1fb12412874c94ad037e11d0ecdd1140a439297; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e759ff76ebbbfcdcf83b6634c54dc47828573d8b; version=2.6.12

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

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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