CVE-2026-89658Hinoki check available

Kernel memory corruption via unpinned NFSD client

Published Sep 11, 2026 · Updated Sep 11, 2026

A use-after-free in Linux 6.9 allows local users to corrupt kernel memory by racing NFSv4.0 client cleanup and expiry. nfs40_clean_admin_revoked() retains a stateid but not its client before dropping client_lock, so nfsd4_drop_revoked_stid() dereferences a client that concurrent teardown has freed. Triggering the race requires a privileged write to the client's ctl file while the periodic NFSD laundromat performs revoked-state cleanup; the documented consequence is a kernel memory-safety fault.

CVSS severityUnavailable
Unscored
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

A use-after-free in Linux 6.9 allows local users to corrupt kernel memory by racing NFSv4.0 client cleanup and expiry. nfs40_clean_admin_revoked() retains a stateid but not its client before dropping client_lock, so nfsd4_drop_revoked_stid() dereferences a client that concurrent teardown has freed. Triggering the race requires a privileged write to the client's ctl file while the periodic NFSD laundromat performs revoked-state cleanup; the documented consequence is a kernel memory-safety fault.

The record

CVE
CVE-2026-89658
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 11, 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?

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  1. Affected versionversion=6.9
  2. Affected versionversion=d688d8585e6bea5e4e37f7497feea93b6b0a469c <0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519
  3. Affected versionversion=d688d8585e6bea5e4e37f7497feea93b6b0a469c <7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55
  4. Affected versionversion=d688d8585e6bea5e4e37f7497feea93b6b0a469c <81cf7f1413862f87b078920c838460a6a88aa030
  5. Affected versionversion=d688d8585e6bea5e4e37f7497feea93b6b0a469c <b413ec5b23e3445dc9c4f273116078e2d4747626

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=6.9; version=d688d8585e6bea5e4e37f7497feea93b6b0a469c <0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519; version=d688d8585e6bea5e4e37f7497feea93b6b0a469c <7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55; version=d688d8585e6bea5e4e37f7497feea93b6b0a469c <81cf7f1413862f87b078920c838460a6a88aa030; version=d688d8585e6bea5e4e37f7497feea93b6b0a469c <b413ec5b23e3445dc9c4f273116078e2d4747626

Published CVSS scores

No CVSS assessment is available in this record.

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

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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