CVE-2025-40087Network attack vector

Unauthenticated NFS service crash via NULL callback

Published Oct 30, 2025 · Updated Aug 5, 2026

Denial of service in Linux NFSD allows remote attackers to crash the NFS service via a FlexFiles LAYOUTCOMMIT request. The NFSv4.1 LAYOUTCOMMIT path unconditionally calls ff_layout_ops.proc_layoutcommit, but FlexFiles leaves that callback NULL in affected kernels. Any host that can reach an exported filesystem using default AUTH_SYS can trigger the kernel oops without server credentials; the oops kills the NFSD thread and can panic the host when panic_on_oops is enabled.

CVSS severity7.5
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Linux NFSD allows remote attackers to crash the NFS service via a FlexFiles LAYOUTCOMMIT request. The NFSv4.1 LAYOUTCOMMIT path unconditionally calls ff_layout_ops.proc_layoutcommit, but FlexFiles leaves that callback NULL in affected kernels. Any host that can reach an exported filesystem using default AUTH_SYS can trigger the kernel oops without server credentials; the oops kills the NFSD thread and can panic the host when panic_on_oops is enabled.

The record

CVE
CVE-2025-40087
Published
Oct 30, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 30, 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=4.8
  2. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <34d187e020cbda112a6c6f094f0ca5e6a8672b75
  3. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <4b47a8601b71ad98833b447d465592d847b4dc77
  4. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <785ec512afa80d0540f2ca797c0e56de747a6083
  5. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <a156af6a4dc38c2aa7c98e89520a70fb3b3e7df4
  6. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <a75994dd879401c3e24ff51c2536559f1a53ea27
  7. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <ba88a53d7f5df4191583abf214214efe0cda91d2
  8. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <da9129ef77786839a3ccd1d7afeeab790bceaa1d
  9. Affected versionversion=9b9960a0ca4773e21c4b153ed355583946346b25 <f7353208c91ab004e0179c5fb6c365b0f132f9f0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.8; version=9b9960a0ca4773e21c4b153ed355583946346b25 <34d187e020cbda112a6c6f094f0ca5e6a8672b75; version=9b9960a0ca4773e21c4b153ed355583946346b25 <4b47a8601b71ad98833b447d465592d847b4dc77; version=9b9960a0ca4773e21c4b153ed355583946346b25 <785ec512afa80d0540f2ca797c0e56de747a6083; version=9b9960a0ca4773e21c4b153ed355583946346b25 <a156af6a4dc38c2aa7c98e89520a70fb3b3e7df4; version=9b9960a0ca4773e21c4b153ed355583946346b25 <a75994dd879401c3e24ff51c2536559f1a53ea27; version=9b9960a0ca4773e21c4b153ed355583946346b25 <ba88a53d7f5df4191583abf214214efe0cda91d2; version=9b9960a0ca4773e21c4b153ed355583946346b25 <da9129ef77786839a3ccd1d7afeeab790bceaa1d; version=9b9960a0ca4773e21c4b153ed355583946346b25 <f7353208c91ab004e0179c5fb6c365b0f132f9f0

Published CVSS scores

7.5LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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.

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Technologies

Your stack

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Your stack

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