CVE-2025-37871Network attack vector

NFS service hang via delegation lock inversion

Published May 9, 2025 · Updated Aug 5, 2026

Denial of service in Linux kernel nfsd allows remote attackers to hang NFS service via conflicting NFSv4 opens. In nfsd_break_one_deleg, a failed callback queue invokes nfs4_put_stid while flc_lock is held, inverting the cl_lock acquisition order. Remote attackers need NFSv4 access to an export; repeated conflicting opens can hang the service or panic hosts configured to abort on warnings.

CVSS severity7.5
High
EPSS probability0.73%
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 kernel nfsd allows remote attackers to hang NFS service via conflicting NFSv4 opens. In nfsd_break_one_deleg, a failed callback queue invokes nfs4_put_stid while flc_lock is held, inverting the cl_lock acquisition order. Remote attackers need NFSv4 access to an export; repeated conflicting opens can hang the service or panic hosts configured to abort on warnings.

The record

CVE
CVE-2025-37871
Published
May 9, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 9, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=133f5e2a37ce08c82d24e8fba65e0a81deae4609 <14985d66b9b99c12995dd99d1c6c8dec4114c2a5
  2. Affected versionversion=230ca758453c63bd38e4d9f4a21db698f7abada8 <a1d14d931bf700c1025db8c46d6731aa5cf440f9
  3. Affected versionversion=5.10.236 <5.10.237
  4. Affected versionversion=5.15.180 <5.15.181
  5. Affected versionversion=6.1.134 <6.1.135
  6. Affected versionversion=6.12.23 <6.12.25
  7. Affected versionversion=6.13.11 <6.14
  8. Affected versionversion=6.14.2 <6.14.4
  9. Affected versionversion=63b91c8ff4589f5263873b24c052447a28e10ef7
  10. Affected versionversion=6.6.87 <6.6.88
  11. Affected versionversion=9a81cde8c7ce65dd90fb47ceea93a45fc1a2fbd1 <7d192e27a431026c58d60edf66dc6cd98d0c01fc
  12. Affected versionversion=b874cdef4e67e5150e07eff0eae1cbb21fb92da1 <b9bbe8f9d5663311d06667ce36d6ed255ead1a26
  13. Affected versionversion=cad3479b63661a399c9df1d0b759e1806e2df3c8 <a7fce086f6ca84db409b9d58493ea77c1978897c
  14. Affected versionversion=cdb796137c57e68ca34518d53be53b679351eb86 <a70832d3555987035fc430ccd703acd89393eadb
  15. Affected versionversion=d96587cc93ec369031bcd7658c6adc719873c9fd <ba903539fff745d592d893c71b30e5e268a95413

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=133f5e2a37ce08c82d24e8fba65e0a81deae4609 <14985d66b9b99c12995dd99d1c6c8dec4114c2a5; version=230ca758453c63bd38e4d9f4a21db698f7abada8 <a1d14d931bf700c1025db8c46d6731aa5cf440f9; version=5.10.236 <5.10.237; version=5.15.180 <5.15.181; version=6.1.134 <6.1.135; version=6.12.23 <6.12.25; version=6.13.11 <6.14; version=6.14.2 <6.14.4; version=63b91c8ff4589f5263873b24c052447a28e10ef7; version=6.6.87 <6.6.88; version=9a81cde8c7ce65dd90fb47ceea93a45fc1a2fbd1 <7d192e27a431026c58d60edf66dc6cd98d0c01fc; version=b874cdef4e67e5150e07eff0eae1cbb21fb92da1 <b9bbe8f9d5663311d06667ce36d6ed255ead1a26; version=cad3479b63661a399c9df1d0b759e1806e2df3c8 <a7fce086f6ca84db409b9d58493ea77c1978897c; version=cdb796137c57e68ca34518d53be53b679351eb86 <a70832d3555987035fc430ccd703acd89393eadb; version=d96587cc93ec369031bcd7658c6adc719873c9fd <ba903539fff745d592d893c71b30e5e268a95413

Published CVSS scores

5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.5Linux kernel CNACVSS: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

T1499Endpoint Denial of Service

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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