VulnerabilityPublished 4 Sep 2025Updated 10 Nov 2026

CVE-2025-38704: Linux kernel · rcu/nocb: Fix possible invalid rdp's->nocb_cb_kthread pointer access

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in cce3d027227c69e85896af9fbc6fa9af5c68f067 : update Linux kernel when convenient.

Data as of 10 Nov 2026, 12:50 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Patch: Available – fixed in cce3d027227c69e85896af9fbc6fa9af5c68f067, b097ae798298885695c339d390b48b4e39619fa7, 9b5ec8e6b31755288a07b3abeeab8cd38e9d3c9d +3

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 3a5761dc025da47960755ac64d9fbf1c32e8cd80, < cce3d027227c69e85896af9fbc6fa9af5c68f067	Fixed in cce3d027227c69e85896af9fbc6fa9af5c68f067
LinuxLinux	Affected ≥ 3a5761dc025da47960755ac64d9fbf1c32e8cd80, < b097ae798298885695c339d390b48b4e39619fa7	Fixed in b097ae798298885695c339d390b48b4e39619fa7
LinuxLinux	Affected ≥ 3a5761dc025da47960755ac64d9fbf1c32e8cd80, < 9b5ec8e6b31755288a07b3abeeab8cd38e9d3c9d	Fixed in 9b5ec8e6b31755288a07b3abeeab8cd38e9d3c9d
LinuxLinux	Affected ≥ 3a5761dc025da47960755ac64d9fbf1c32e8cd80, < 3da45ec1e485a1a5ad31fe9ddd467c7ee5ae4ef9	Fixed in 3da45ec1e485a1a5ad31fe9ddd467c7ee5ae4ef9
LinuxLinux	Affected ≥ 3a5761dc025da47960755ac64d9fbf1c32e8cd80, < 1c951683a720b17c9ecaad1932bc95b29044611f	Fixed in 1c951683a720b17c9ecaad1932bc95b29044611f
LinuxLinux	Affected ≥ 3a5761dc025da47960755ac64d9fbf1c32e8cd80, < 1bba3900ca18bdae28d1b9fa10f16a8f8cb2ada1	Fixed in 1bba3900ca18bdae28d1b9fa10f16a8f8cb2ada1

AI-suggested

This vulnerability has been fixed in the Linux kernel. Users should apply the official patches or update to a fixed kernel version containing the commits identified by the fixedVersions hashes. No additional mitigation is required beyond applying the fix.

Description

A vulnerability in the Linux kernel's rcu/nocb subsystem could lead to invalid pointer access during CPU online/offline operations. Specifically, a failure in creating rcuop kthreads for a CPU's rdp structure can cause an invalid rdp->nocb_cb_kthread pointer to be accessed during subsequent re-offload operations. This issue has been fixed by changing the pointer used for safety checks to prevent invalid access.

Impact

The vulnerability can cause invalid pointer dereference in kernel code during CPU online/offline operations, which may lead to kernel crashes or instability. There is no indication of remote exploitation or privilege escalation from the provided data.

Summary

CVE-2025-38704 addresses a flaw in the Linux kernel's rcu/nocb code where, during CPU online preparation, failure to create the rdp's rcuop kthreads can result in the rdp->nocb_cb_kthread pointer being unassigned while related pointers remain valid. Subsequent re-offload operations on the offline CPU pass conditional checks and invoke kthread_unpark() on an invalid rdp->nocb_cb_kthread pointer, potentially causing kernel instability or crashes. The fix replaces the use of rdp->nocb_cb_kthread with rdp->nocb_gp_kthread for the safety check to avoid invalid pointer dereference.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Nov 2026, 12:50 UTC

Technical details

References

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