CVE-2021-47274

Kernel crash via incomplete ftrace buffer length check

Published May 21, 2024 · Updated Aug 5, 2026

Out-of-bounds write in Linux kernel ftrace allows attackers to corrupt kernel memory and crash the system via oversized trace data. The filter-buffer length check omits sizeof entry->array[0], even though that element stores the trace-data length, so string fetches can write past the allocation. Reachability requires CONFIG_KPROBE_EVENTS and an enabled kprobe that fetches an oversized string; the demonstrated consequence is a general-protection fault and kernel crash.

CVSS severity9.8
Critical
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Linux kernel ftrace allows attackers to corrupt kernel memory and crash the system via oversized trace data. The filter-buffer length check omits sizeof entry->array[0], even though that element stores the trace-data length, so string fetches can write past the allocation. Reachability requires CONFIG_KPROBE_EVENTS and an enabled kprobe that fetches an oversized string; the demonstrated consequence is a general-protection fault and kernel crash.

The record

CVE
CVE-2021-47274
Published
May 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=0572fc6a510add9029b113239eaabf4b5bce8ec9 <31ceae385556c37e4d286cb6378696448f566883
  2. Affected versionversion=2e584b1a02eeb860e286d39bc408b25ebc5ec844 <edcce01e0e50840a9aa6a70baed21477bdd2c9f9
  3. Affected versionversion=4.14.222 <4.14.237
  4. Affected versionversion=4.19.177 <4.19.195
  5. Affected versionversion=4.9.258 <4.9.273
  6. Affected versionversion=5.10.17 <5.10.44
  7. Affected versionversion=5.11
  8. Affected versionversion=5.4.99 <5.4.126
  9. Affected versionversion=7c93d8cff582c459350d6f8906eea6e4cd60d959 <43c32c22254b9328d7abb1c2b0f689dc67838e60
  10. Affected versionversion=a0997a86f5c0085e183ddee5fb72091d584d3d16 <d63f00ec908b3be635ead5d6029cc94246e1f38d
  11. Affected versionversion=b220c049d5196dd94d992dd2dc8cba1a5e6123bf <3e08a9f9760f4a70d633c328a76408e62d6f80a3
  12. Affected versionversion=b220c049d5196dd94d992dd2dc8cba1a5e6123bf <b16a249eca2230c2cd66fa1d4b94743bd9b6ef92
  13. Affected versionversion=e46d433754420b4d6513ca389403de88a0910279 <2d598902799886d67947406f26ee8e5fd2ca097f

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linuxversion=0572fc6a510add9029b113239eaabf4b5bce8ec9 <31ceae385556c37e4d286cb6378696448f566883; version=2e584b1a02eeb860e286d39bc408b25ebc5ec844 <edcce01e0e50840a9aa6a70baed21477bdd2c9f9; version=4.14.222 <4.14.237; version=4.19.177 <4.19.195; version=4.9.258 <4.9.273; version=5.10.17 <5.10.44; version=5.11; version=5.4.99 <5.4.126; version=7c93d8cff582c459350d6f8906eea6e4cd60d959 <43c32c22254b9328d7abb1c2b0f689dc67838e60; version=a0997a86f5c0085e183ddee5fb72091d584d3d16 <d63f00ec908b3be635ead5d6029cc94246e1f38d; version=b220c049d5196dd94d992dd2dc8cba1a5e6123bf <3e08a9f9760f4a70d633c328a76408e62d6f80a3; version=b220c049d5196dd94d992dd2dc8cba1a5e6123bf <b16a249eca2230c2cd66fa1d4b94743bd9b6ef92; version=e46d433754420b4d6513ca389403de88a0910279 <2d598902799886d67947406f26ee8e5fd2ca097f
The Linux Kernel Organization · Linux Kernelversion=0572fc6a510a <31ceae385556; version=2e584b1a02ee <edcce01e0e50; version=5.11; version=7c93d8cff582 <43c32c22254b; version=a0997a86f5c0 <d63f00ec908b; version=b220c049d519 <3e08a9f9760f; version=b220c049d519 <b16a249eca22; version=e46d43375442 <2d5989027998

Published CVSS scores

9.8CanonicalCVSS:3.1/AV:N/AC:L/PR:N/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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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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