CVE-2026-89685Network attack vectorHinoki check available

Remote service denial via mixed clock domains

Published Sep 11, 2026 · Updated Sep 11, 2026

Denial of service in Linux kernel nfsd allows remote attackers to block non-reclaim NFS operations indefinitely via NFSv4 OPEN requests. clients_still_reclaiming() derives its deadline from a CLOCK_REALTIME boot value but compares it with CLOCK_BOOTTIME, causing the grace-expiration test to remain false. Any network client able to send CLAIM_PREVIOUS requests during grace can retain that state and interrupt file operations for other clients without crashing the host.

CVSS severityUnavailable
Unscored
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Denial of service in Linux kernel nfsd allows remote attackers to block non-reclaim NFS operations indefinitely via NFSv4 OPEN requests. clients_still_reclaiming() derives its deadline from a CLOCK_REALTIME boot value but compares it with CLOCK_BOOTTIME, causing the grace-expiration test to remain false. Any network client able to send CLAIM_PREVIOUS requests during grace can retain that state and interrupt file operations for other clients without crashing the host.

The record

CVE
CVE-2026-89685
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=20b7d86f29d39e8ae19bb29c24ffee70dc385ddf <09ea3eb9a518565f5bca386e81b993ed8825f5e8
  2. Affected versionversion=20b7d86f29d39e8ae19bb29c24ffee70dc385ddf <9843649196221152b6e5d138a3ce859bdaae1d96
  3. Affected versionversion=20b7d86f29d39e8ae19bb29c24ffee70dc385ddf <f9cec313efb2fd18d962aad738a4892bce806016
  4. Affected versionversion=5.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=20b7d86f29d39e8ae19bb29c24ffee70dc385ddf <09ea3eb9a518565f5bca386e81b993ed8825f5e8; version=20b7d86f29d39e8ae19bb29c24ffee70dc385ddf <9843649196221152b6e5d138a3ce859bdaae1d96; version=20b7d86f29d39e8ae19bb29c24ffee70dc385ddf <f9cec313efb2fd18d962aad738a4892bce806016; version=5.6

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

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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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