CVE-2022-50344

Kernel crash via ext4 unmount NULL dereference

Published Sep 16, 2025 · Updated Sep 16, 2025

NULL pointer dereference in Linux kernel ext4 allows local users to crash the kernel while an ext4 filesystem is unmounted. ext4_write_info passes d_inode(sb->s_root) to ext4_journal_start after shrink_dcache_for_umount has cleared sb->s_root, so quota writeback dereferences a null root dentry. Triggering requires local low-privileged access and the ext4 unmount-time quota writeback path; the bounded consequence is a kernel crash.

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

What happened

NULL pointer dereference in Linux kernel ext4 allows local users to crash the kernel while an ext4 filesystem is unmounted. ext4_write_info passes d_inode(sb->s_root) to ext4_journal_start after shrink_dcache_for_umount has cleared sb->s_root, so quota writeback dereferences a null root dentry. Triggering requires local low-privileged access and the ext4 unmount-time quota writeback path; the bounded consequence is a kernel crash.

The record

CVE
CVE-2022-50344
Published
Sep 16, 2025
Updated
Sep 16, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3638aa1c7d87c0ca0aef23cf58cae2c48e7daca4
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4a657319cfabd6199fd0b7b65bbebf6ded7a11c1
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <533c60a0b97cee5daab376933f486207e6680fb7
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <947264e00c46de19a016fd81218118c708fed2f3
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bb420e8afc854d2a1caaa23a0c129839acfb7888
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dc451578446afd03c0c21913993c08898a691435
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f34ab95162763cd7352f46df169296eec28b688d
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f4b5ff0b794aa94afac7269c494550ca2f66511b
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f9c1f248607d5546075d3f731e7607d5571f2b60

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3638aa1c7d87c0ca0aef23cf58cae2c48e7daca4; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4a657319cfabd6199fd0b7b65bbebf6ded7a11c1; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <533c60a0b97cee5daab376933f486207e6680fb7; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <947264e00c46de19a016fd81218118c708fed2f3; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bb420e8afc854d2a1caaa23a0c129839acfb7888; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dc451578446afd03c0c21913993c08898a691435; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f34ab95162763cd7352f46df169296eec28b688d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f4b5ff0b794aa94afac7269c494550ca2f66511b; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <f9c1f248607d5546075d3f731e7607d5571f2b60

Published CVSS scores

5.5CISA-ADPCVSS: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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