CVE-2025-38643 – A race condition vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2025-38643?

CVE-2025-38643 has a CVSS score of 5.5 (MEDIUM). A race condition vulnerability in the Linux kernel's WiFi subsystem where cfg80211_propagate_cac_done_wk worker fails to acquire the required wiphy mutex before calling wdev_chandef(). This can trigger kernel warnings and potential system instability. Affects Linux systems with WiFi functionality enabled, particularly those using mesh networking or DFS channels.

📋 TL;DR

A race condition vulnerability in the Linux kernel's WiFi subsystem where cfg80211_propagate_cac_done_wk worker fails to acquire the required wiphy mutex before calling wdev_chandef(). This can trigger kernel warnings and potential system instability. Affects Linux systems with WiFi functionality enabled, particularly those using mesh networking or DFS channels.

💻 Affected Systems

Products:

Linux kernel

Versions: Linux kernel versions before fixes in stable trees (specific commits: 2c5dee15239f3f3e31aa5c8808f18996c039e2c1, 4a63523d3541eef4cf504a9682e6fbe94ffe79a6, 7022df2248c08c6f75a01714163ac902333bf3db, b3d24038eb775f2f7a1dfef58d8e1dc444a12820, dbce810607726408f889d3358f4780fd1436861e)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires WiFi functionality enabled and specific conditions with mesh networking or DFS channel usage

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

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Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

Learn more about Linux Kernel →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Kernel panic or system crash due to race condition leading to memory corruption or deadlock

🟠

Likely Case

Kernel warning messages in system logs and potential WiFi connectivity issues or instability

🟢

If Mitigated

Minor performance impact from proper locking with no security compromise

🌐 Internet-Facing: LOW - Requires local access to WiFi interface and specific conditions

🏢 Internal Only: MEDIUM - Could affect internal network stability on vulnerable systems

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires specific timing conditions and WiFi configuration. More likely to cause stability issues than privilege escalation.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel with commits from stable trees listed in references

Vendor Advisory: https://git.kernel.org/stable/c/2c5dee15239f3f3e31aa5c8808f18996c039e2c1

Restart Required: No

Instructions:

1. Update Linux kernel to version containing the fix commits. 2. For distributions: Use package manager to update kernel package. 3. For custom kernels: Apply the relevant patch from kernel.org stable trees. 4. Rebuild and install kernel if compiling from source.

🔧 Temporary Workarounds

Disable WiFi mesh and DFS features

all

Prevent triggering the vulnerable code path by disabling mesh networking and DFS channel support

iw dev wlan0 set type managed
Disable mesh mode in hostapd/wpa_supplicant configs

🧯 If You Can't Patch

Monitor system logs for kernel warnings related to wdev_chandef or cfg80211
Avoid using WiFi mesh networking features and DFS channels on affected systems

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if WiFi is enabled. Look for kernel warnings in dmesg containing 'wdev_chandef' or 'cfg80211_propagate_cac_done_wk'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits. Test WiFi mesh functionality and monitor for absence of related kernel warnings

📡 Detection & Monitoring

Log Indicators:

Kernel warning messages containing 'wdev_chandef', 'cfg80211_propagate_cac_done_wk', or 'WARNING: CPU:' with stack traces from wireless/chan.c

Network Indicators:

Unusual WiFi disconnections or instability when using mesh networking

SIEM Query:

source="kernel" AND ("wdev_chandef" OR "cfg80211_propagate_cac_done_wk" OR "wireless/chan.c:1552")

📊 Metadata

CVE ID: CVE-2025-38643

CVSS v3 Score: 5.5 (MEDIUM)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-667

EPSS Score: 0.01% exploit probability (1.4th percentile)

Published: August 22, 2025

Last Updated: February 19, 2026

🔗 References

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