CVE-2021-3428

System crash via ext4 extent integer overflow

Published Mar 4, 2022 · Updated Aug 3, 2024

Integer overflow in Linux Kernel before 5.9 allows local users to crash the system by mounting a crafted ext4 filesystem image. The ext4 extent-cache path accepts unchecked journal-inode extents, then ext4_es_cache_extent computes lblk + len in 32 bits and triggers a kernel BUG on wraparound. Exploitation requires permission to mount an attacker-controlled filesystem and causes an availability-only system crash.

CVSS severity5.5
Medium
EPSS probability0.30%
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 Linux Kernel before 5.9 allows local users to crash the system by mounting a crafted ext4 filesystem image. The ext4 extent-cache path accepts unchecked journal-inode extents, then ext4_es_cache_extent computes lblk + len in 32 bits and triggers a kernel BUG on wraparound. Exploitation requires permission to mount an attacker-controlled filesystem and causes an availability-only system crash.

The record

CVE
CVE-2021-3428
Published
Mar 4, 2022
Updated
Aug 3, 2024
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-190, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 4, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=Affects linux kernel before v5.9.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=Affects linux kernel before v5.9.

Published CVSS scores

4.9NIST NVDAV:L/AC:L/Au:N/C:N/I:N/A:C
5.5NIST NVDCVSS: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.

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

CWE-190Integer Overflow or Wraparound
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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