CVE-2026-89706Network attack vector

Silent copied-data loss via stale write verifier

Published Sep 11, 2026 · Updated Sep 11, 2026

Improper write-verifier handling in Linux nfsd allows remote authenticated users to receive false durability confirmation after writeback fails. The _nfsd_copy_file_range() error path reports NFS_UNSTABLE but leaves nn->writeverf unchanged, so the later COMMIT falsely confirms durability. Reachability requires an authorized NFSv4.2 client, asynchronous COPY, and a post-copy writeback failure; the loss is limited to copied data whose writeback failed.

CVSS severityUnavailable
Unscored
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper write-verifier handling in Linux nfsd allows remote authenticated users to receive false durability confirmation after writeback fails. The _nfsd_copy_file_range() error path reports NFS_UNSTABLE but leaves nn->writeverf unchanged, so the later COMMIT falsely confirms durability. Reachability requires an authorized NFSv4.2 client, asynchronous COPY, and a post-copy writeback failure; the loss is limited to copied data whose writeback failed.

The record

CVE
CVE-2026-89706
Published
Sep 11, 2026
Updated
Sep 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
Unavailable
Attack vector
network
Privileges
authenticated

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=5.10.220 <5.11
  2. Affected versionversion=5.14
  3. Affected versionversion=817c6eb975798647c4bbbfc9eb288aa413ec7f65
  4. Affected versionversion=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0
  5. Affected versionversion=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <591134e059e3456180244a826d6917cdc183140b
  6. Affected versionversion=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <bf0cd31a9abcb728c17d79b4c2cc533612a8b6af
  7. Affected versionversion=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.10.220 <5.11; version=5.14; version=817c6eb975798647c4bbbfc9eb288aa413ec7f65; version=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0; version=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <591134e059e3456180244a826d6917cdc183140b; version=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <bf0cd31a9abcb728c17d79b4c2cc533612a8b6af; version=eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d <f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
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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