CVE-2025-40212Network attack vector

Remote service crash via stale export reference

Published Nov 24, 2025 · Updated Nov 24, 2025

Use-after-free in Linux kernel nfsd 6.12 allows remote attackers to crash the server via a synthesized NFSv2 or NFSv3 filehandle. nfsd_set_fh_dentry() stores an export in struct svc_fh after exp_put() drops its reference, so fh_put() later drops the same reference again. The path requires an NFS client to synthesize a pseudo-root filehandle that normal NFSv2 or NFSv3 operation does not provide.

CVSS severity9.8
Critical
EPSS probability0.40%
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 kernel nfsd 6.12 allows remote attackers to crash the server via a synthesized NFSv2 or NFSv3 filehandle. nfsd_set_fh_dentry() stores an export in struct svc_fh after exp_put() drops its reference, so fh_put() later drops the same reference again. The path requires an NFS client to synthesize a pseudo-root filehandle that normal NFSv2 or NFSv3 operation does not provide.

The record

CVE
CVE-2025-40212
Published
Nov 24, 2025
Updated
Nov 24, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 24, 2025CVE publishedPublication date reported by the CVE source.
  2. Nov 24, 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=6.12
  2. Affected versionversion=ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444 <8a7348a9ed70bda1c1f51d3f1815bcbdf9f3b38c
  3. Affected versionversion=ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444 <b6bc86ce3944b10b9fc181fc00c1a520a20ed965
  4. Affected versionversion=ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444 <c83d7365cec5eb5ebeeee2a72e29b4ca58a7e4c2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.12; version=ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444 <8a7348a9ed70bda1c1f51d3f1815bcbdf9f3b38c; version=ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444 <b6bc86ce3944b10b9fc181fc00c1a520a20ed965; version=ef7f6c4904d03ccd7478e1ac20ed75f79c4ac444 <c83d7365cec5eb5ebeeee2a72e29b4ca58a7e4c2

Published CVSS scores

9.8Linux Kernel CVE teamCVSS:3.1/AV:N/AC:L/PR:N/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)
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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