CVE-2021-47458

Kernel crash via unterminated OCFS2 cluster strings

Published May 22, 2024 · Updated Aug 5, 2026

Out-of-bounds read in Linux kernel OCFS2 allows local users to crash the kernel by mounting a crafted filesystem image. In ocfs2_initialize_super, strlcpy scans fixed-width, non-null-terminated cluster-stack and cluster-name fields as C strings, reading beyond each source field. The path requires an OCFS2 image using the o2cb or pcmk stack on a CONFIG_FORTIFY_SOURCE build; the demonstrated consequence is a kernel panic.

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

Out-of-bounds read in Linux kernel OCFS2 allows local users to crash the kernel by mounting a crafted filesystem image. In ocfs2_initialize_super, strlcpy scans fixed-width, non-null-terminated cluster-stack and cluster-name fields as C strings, reading beyond each source field. The path requires an OCFS2 image using the o2cb or pcmk stack on a CONFIG_FORTIFY_SOURCE build; the demonstrated consequence is a kernel panic.

The record

CVE
CVE-2021-47458
Published
May 22, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 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=3.14
  2. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <0e677ea5b7396f715a76b6b0ef441430e4c4b57f
  3. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <232ed9752510de4436468b653d145565669c8498
  4. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <4b74ddcc22ee6455946e80a9c4808801f8f8561e
  5. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <7623b1035ca2d17bde0f6a086ad6844a34648df1
  6. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <93be0eeea14cf39235e585c8f56df3b3859deaad
  7. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <ac011cb3ff7a76b3e0e6e77158ee4ba2f929e1fb
  8. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <b15fa9224e6e1239414525d8d556d824701849fc
  9. Affected versionversion=c74a3bdd9b529d924d1abf986079b783dd105ace <d3a83576378b4c904f711598dde2c5e881c4295c

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.14; version=c74a3bdd9b529d924d1abf986079b783dd105ace <0e677ea5b7396f715a76b6b0ef441430e4c4b57f; version=c74a3bdd9b529d924d1abf986079b783dd105ace <232ed9752510de4436468b653d145565669c8498; version=c74a3bdd9b529d924d1abf986079b783dd105ace <4b74ddcc22ee6455946e80a9c4808801f8f8561e; version=c74a3bdd9b529d924d1abf986079b783dd105ace <7623b1035ca2d17bde0f6a086ad6844a34648df1; version=c74a3bdd9b529d924d1abf986079b783dd105ace <93be0eeea14cf39235e585c8f56df3b3859deaad; version=c74a3bdd9b529d924d1abf986079b783dd105ace <ac011cb3ff7a76b3e0e6e77158ee4ba2f929e1fb; version=c74a3bdd9b529d924d1abf986079b783dd105ace <b15fa9224e6e1239414525d8d556d824701849fc; version=c74a3bdd9b529d924d1abf986079b783dd105ace <d3a83576378b4c904f711598dde2c5e881c4295c

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
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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