CVE-2025-38704

Kernel crash via invalid RCU kthread pointer

Published Sep 4, 2025 · Updated Sep 8, 2026

Improper validation in Linux kernel RCU nocb CPU re-offloading allows local users to crash the kernel through an invalid kthread pointer. After rcuop thread creation fails, de-offloading leaves related pointers valid but nocb_cb_kthread unset, so re-offloading passes the wrong guard and unparks an invalid pointer. Reachability requires CAP_SYS_MODULE to load rcutorture, the only in-tree caller of rcu_nocb_cpu_offload; exploitation interrupts the system.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper validation in Linux kernel RCU nocb CPU re-offloading allows local users to crash the kernel through an invalid kthread pointer. After rcuop thread creation fails, de-offloading leaves related pointers valid but nocb_cb_kthread unset, so re-offloading passes the wrong guard and unparks an invalid pointer. Reachability requires CAP_SYS_MODULE to load rcutorture, the only in-tree caller of rcu_nocb_cpu_offload; exploitation interrupts the system.

The record

CVE
CVE-2025-38704
Published
Sep 4, 2025
Updated
Sep 8, 2026
Vendor
Siemens
Product
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classifications
CWE-20
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Sep 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 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 <*
  2. Affected versionversion=V3.1.6 <*

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

Siemens · SIPLUS S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*
The Linux Kernel Organization · Linuxversion=3a5761dc025da47960755ac64d9fbf1c32e8cd80 <1bba3900ca18bdae28d1b9fa10f16a8f8cb2ada1; version=3a5761dc025da47960755ac64d9fbf1c32e8cd80 <1c951683a720b17c9ecaad1932bc95b29044611f; version=3a5761dc025da47960755ac64d9fbf1c32e8cd80 <3da45ec1e485a1a5ad31fe9ddd467c7ee5ae4ef9; version=3a5761dc025da47960755ac64d9fbf1c32e8cd80 <9b5ec8e6b31755288a07b3abeeab8cd38e9d3c9d; version=3a5761dc025da47960755ac64d9fbf1c32e8cd80 <b097ae798298885695c339d390b48b4e39619fa7; version=3a5761dc025da47960755ac64d9fbf1c32e8cd80 <cce3d027227c69e85896af9fbc6fa9af5c68f067; version=6.0
Siemens · SIMATIC S7-1500 CPU 1518F-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*
Siemens · SIMATIC S7-1500 CPU 1518-4 PN/DP MFPversion=V3.1.5 <*; version=V3.1.6 <*

Published CVSS scores

7.8UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation

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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