CVE-2021-33631

Kernel crash via stale EXT4 inline-data state

Published Jan 18, 2024 · Updated Feb 13, 2025

Integer overflow in the EXT4 filesystem of openEuler Kernel allows local users to crash affected systems through crafted inline-data writes. ext4_write_end checks for inline data but fails to verify the EXT4_STATE_MAY_INLINE_DATA flag before calling ext4_write_inline_data_end, triggering a kernel BUG after inline-data conversion begins. The issue affects the 4.19.90 line before 4.19.90-2401.3 and the 5.10.0-60.18.0 line before 5.10.0-183.0.0; exploitation requires local low-privileged access.

CVSS severity5.5
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in the EXT4 filesystem of openEuler Kernel allows local users to crash affected systems through crafted inline-data writes. ext4_write_end checks for inline data but fails to verify the EXT4_STATE_MAY_INLINE_DATA flag before calling ext4_write_inline_data_end, triggering a kernel BUG after inline-data conversion begins. The issue affects the 4.19.90 line before 4.19.90-2401.3 and the 5.10.0-60.18.0 line before 5.10.0-183.0.0; exploitation requires local low-privileged access.

The record

CVE
CVE-2021-33631
Published
Jan 18, 2024
Updated
Feb 13, 2025
Vendor
openEuler
Product
openEuler Kernel
Classifications
CWE-190, CAPEC-92, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 18, 2024CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=4.19.90 <4.19.90-2401.3 changes=[{"at":"cf1d16ea2f1086c0765348344b70aa2361436642 ext4: fix kernel BUG in 'ext4_write_inline_data_end()'","status":"unaffected"}]
  2. Affected versionversion=5.10.0-60.18.0 <5.10.0-183.0.0 changes=[{"at":"1587126a0f2a79b3ee6cb309bbfaf079c39eda29 ext4: fix kernel BUG in 'ext4_write_inline_data_end()'","status":"unaffected"}]

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

openEuler · openEuler Kernelversion=4.19.90 <4.19.90-2401.3 changes=[{"at":"cf1d16ea2f1086c0765348344b70aa2361436642 ext4: fix kernel BUG in 'ext4_write_inline_data_end()'","status":"unaffected"}]; version=5.10.0-60.18.0 <5.10.0-183.0.0 changes=[{"at":"1587126a0f2a79b3ee6cb309bbfaf079c39eda29 ext4: fix kernel BUG in 'ext4_write_inline_data_end()'","status":"unaffected"}]

Published CVSS scores

5.5openEulerCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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-190Integer Overflow or Wraparound
CAPEC-92Forced Integer Overflow
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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