CVE-2025-38393Network attack vector

Remote writeback hang via missed layout wakeup

Published Jul 25, 2025 · Updated Aug 5, 2026

A race in Linux NFSv4/pNFS clients allows remote attackers to hang writeback through a malicious or intercepted server. pnfs_update_layout() can sleep on NFS_LAYOUT_DRAIN after nfs_layoutget_end() clears the final outstanding layout and calls wake_up_bit() without the required memory barrier. An existing pNFS mount with ongoing I/O is required; repeated layout recalls or invalid-state replies can leave kernel tasks blocked indefinitely.

CVSS severity4.7
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

A race in Linux NFSv4/pNFS clients allows remote attackers to hang writeback through a malicious or intercepted server. pnfs_update_layout() can sleep on NFS_LAYOUT_DRAIN after nfs_layoutget_end() clears the final outstanding layout and calls wake_up_bit() without the required memory barrier. An existing pNFS mount with ongoing I/O is required; repeated layout recalls or invalid-state replies can leave kernel tasks blocked indefinitely.

The record

CVE
CVE-2025-38393
Published
Jul 25, 2025
Updated
Aug 5, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-362, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 25, 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=V3.1.5 <*

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*
The Linux Kernel Organization · Linuxversion=5.10.124 <5.10.240; version=5.15.49 <5.15.187; version=5.18.6 <5.19; version=5.19; version=880265c77ac415090090d1fe72a188fee71cb458 <1f4da20080718f258e189a2c5f515385fa393da6; version=880265c77ac415090090d1fe72a188fee71cb458 <864a54c1243ed3ca60baa4bc492dede1361f4c83; version=880265c77ac415090090d1fe72a188fee71cb458 <8ca65fa71024a1767a59ffbc6a6e2278af84735e; version=880265c77ac415090090d1fe72a188fee71cb458 <c01776287414ca43412d1319d2877cbad65444ac; version=880265c77ac415090090d1fe72a188fee71cb458 <e4b13885e7ef1e64e45268feef1e5f0707c47e72; version=8acc3e228e1c90bd410f73597a4549e0409f22d6 <08287df60bac5b008b6bcdb03053988335d3d282; version=ec23a86e060cbe30b62eb2955adc97c92d80cc4c <8846fd02c98da8b79e6343a20e6071be6f372180; version=f133819e24e78f3aaaa00e9fa2b816d5f73fd172
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.5 <*
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/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

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
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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