CVE-2022-49834

Kernel crash via remount synchronization race

Published May 1, 2025 · Updated Aug 5, 2026

Use-after-free in Linux nilfs2 allows local users to crash the kernel by racing a filesystem remount with synchronization. nilfs_remount can detach and free nilfs->ns_writer while nilfs_segctor_sync sleeps, after which finish_wait dereferences the freed log writer. Reaching the race requires a mounted nilfs2 block-device filesystem and CAP_SYS_ADMIN in the initial user namespace to remount it.

CVSS severity7.8
High
EPSS probability0.22%
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 Linux nilfs2 allows local users to crash the kernel by racing a filesystem remount with synchronization. nilfs_remount can detach and free nilfs->ns_writer while nilfs_segctor_sync sleeps, after which finish_wait dereferences the freed log writer. Reaching the race requires a mounted nilfs2 block-device filesystem and CAP_SYS_ADMIN in the initial user namespace to remount it.

The record

CVE
CVE-2022-49834
Published
May 1, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. May 1, 2025CVE 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=2.6.34
  2. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <39a3ed68270b079c6b874d4e4727a512b9b4882c
  3. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <4feedde5486c07ea79787839153a71ca71329c7d
  4. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <8cccf05fe857a18ee26e20d11a8455a73ffd4efd
  5. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <9b162e81045266a2d5b44df9dffdf05c54de9cca
  6. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <afbd1188382a75f6cfe22c0b68533f7f9664f182
  7. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <b152300d5a1ba4258dacf9916bff20e6a8c7603b
  8. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <b2fbf10040216ef5ee270773755fc2f5da65b749
  9. Affected versionversion=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <b4736ab5542112fe0a40f140a0a0b072954f34da

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.34; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <39a3ed68270b079c6b874d4e4727a512b9b4882c; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <4feedde5486c07ea79787839153a71ca71329c7d; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <8cccf05fe857a18ee26e20d11a8455a73ffd4efd; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <9b162e81045266a2d5b44df9dffdf05c54de9cca; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <afbd1188382a75f6cfe22c0b68533f7f9664f182; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <b152300d5a1ba4258dacf9916bff20e6a8c7603b; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <b2fbf10040216ef5ee270773755fc2f5da65b749; version=fe5f171bb272946ce5fbf843ce2f8467d0d41b9a <b4736ab5542112fe0a40f140a0a0b072954f34da

Published CVSS scores

7.8Linux kernelCVSS: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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
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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