CVE-2021-47004

Kernel panic and data corruption via victim misselection

Published Feb 28, 2024 · Updated Aug 5, 2026

F2FS victim-selection errors in affected Linux kernel versions allow local users to corrupt data or trigger a kernel panic during block allocation. In get_victim(), LFS checks checkpointed valid blocks only in the current segment rather than the entire section, while SSR and AT_SSR can select a target segment with no free blocks. Exploitation requires write access to an F2FS filesystem mounted with checkpointing disabled and affects integrity and availability.

CVSS severity7.1
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

F2FS victim-selection errors in affected Linux kernel versions allow local users to corrupt data or trigger a kernel panic during block allocation. In get_victim(), LFS checks checkpointed valid blocks only in the current segment rather than the entire section, while SSR and AT_SSR can select a target segment with no free blocks. Exploitation requires write access to an F2FS filesystem mounted with checkpointing disabled and affects integrity and availability.

The record

CVE
CVE-2021-47004
Published
Feb 28, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 28, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.20
  2. Affected versionversion=4354994f097d068a894aa1a0860da54571df3582 <105155a8146ddb54c119d8318964eef3859d109d
  3. Affected versionversion=4354994f097d068a894aa1a0860da54571df3582 <1e116f87825f01a6380286472196882746b16f63
  4. Affected versionversion=4354994f097d068a894aa1a0860da54571df3582 <211372b2571520e394b56b431a0705586013b3ff
  5. Affected versionversion=4354994f097d068a894aa1a0860da54571df3582 <61461fc921b756ae16e64243f72af2bfc2e620db

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.20; version=4354994f097d068a894aa1a0860da54571df3582 <105155a8146ddb54c119d8318964eef3859d109d; version=4354994f097d068a894aa1a0860da54571df3582 <1e116f87825f01a6380286472196882746b16f63; version=4354994f097d068a894aa1a0860da54571df3582 <211372b2571520e394b56b431a0705586013b3ff; version=4354994f097d068a894aa1a0860da54571df3582 <61461fc921b756ae16e64243f72af2bfc2e620db

Published CVSS scores

7.1kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

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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