CVE-2021-47335

Kernel crash via global slab-cache lifecycle race

Published May 21, 2024 · Updated Aug 11, 2026

Use-after-free in the Linux f2fs recovery path allows local users to crash the kernel by racing mounts of multiple filesystems. The global fsync_entry_slab pointer is created and destroyed per mount, so one f2fs instance can destroy the cache while another recovery path still writes through it. The scored gate is local low-privileged access, concurrent f2fs mount or recovery activity must occur, and the reported impact is limited to service interruption.

CVSS severity5.5
Medium
EPSS probability0.23%
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 f2fs recovery path allows local users to crash the kernel by racing mounts of multiple filesystems. The global fsync_entry_slab pointer is created and destroyed per mount, so one f2fs instance can destroy the cache while another recovery path still writes through it. The scored gate is local low-privileged access, concurrent f2fs mount or recovery activity must occur, and the reported impact is limited to service interruption.

The record

CVE
CVE-2021-47335
Published
May 21, 2024
Updated
Aug 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 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=3.8
  2. Affected versionversion=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <79fa5d944c875711253a23b8155b36883c696409
  3. Affected versionversion=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <86786603014e0a22d0d6af8e80ae4b8687927048
  4. Affected versionversion=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <cad83c968c2ebe97905f900326988ed37146c347
  5. Affected versionversion=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <e472b276a0d2180808009be38105e12754432e2a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.8; version=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <79fa5d944c875711253a23b8155b36883c696409; version=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <86786603014e0a22d0d6af8e80ae4b8687927048; version=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <cad83c968c2ebe97905f900326988ed37146c347; version=d624c96fb3249e5d3dcf4e60a805e5e6b0dd7d91 <e472b276a0d2180808009be38105e12754432e2a

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
T1499Endpoint Denial of Service

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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