CVE-2025-38641
📋 TL;DR
This CVE describes a NULL pointer dereference vulnerability in the Linux kernel's Bluetooth USB driver (btusb). If exploited, it could cause a kernel panic or system crash when Bluetooth USB devices are connected. Systems running vulnerable Linux kernel versions with Bluetooth hardware are affected.
💻 Affected Systems
- Linux kernel
📦 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...
Learn more about Linux Kernel →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially requiring physical access or reboot to restore functionality.
Likely Case
System instability or crash when specific Bluetooth USB devices are connected, resulting in temporary denial of service.
If Mitigated
No impact if the system doesn't use Bluetooth USB devices or if the vulnerable code path isn't triggered.
🎯 Exploit Status
Exploitation requires triggering the specific kmalloc failure condition and subsequent NULL dereference, which may be difficult to reliably achieve
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in stable kernel commits 5029d80bfc30b60ff57c70ccb04e027acb404f6a and b505902c66a282dcb01bcdc015aa1fdfaaa075db
Vendor Advisory: https://git.kernel.org/stable/c/5029d80bfc30b60ff57c70ccb04e027acb404f6a
Restart Required: No
Instructions:
1. Update to a patched Linux kernel version from your distribution's repositories. 2. For custom kernels, apply the patches from the stable kernel tree. 3. Rebuild and install the kernel if compiling from source.
🔧 Temporary Workarounds
Disable Bluetooth USB support
allPrevent the vulnerable code from being loaded by disabling Bluetooth USB driver
echo 'blacklist btusb' >> /etc/modprobe.d/blacklist-btusb.conf
rmmod btusb
Disable Bluetooth hardware
allTurn off Bluetooth functionality at hardware level
rfkill block bluetooth
🧯 If You Can't Patch
- Disable Bluetooth USB devices and drivers to prevent exploitation
- Implement strict physical access controls to prevent unauthorized Bluetooth device connections
🔍 How to Verify
Check if Vulnerable:
Check if the btusb module is loaded: lsmod | grep btusb. If loaded and kernel version is unpatched, system may be vulnerable.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the patch commits or is newer than the patched versions. Check dmesg for any btusb-related crashes after patch.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages in /var/log/kern.log or dmesg
- NULL pointer dereference errors mentioning btusb or Bluetooth
Network Indicators:
- Unusual Bluetooth connection attempts followed by system instability
SIEM Query:
source="kernel" AND ("NULL pointer dereference" OR "kernel panic") AND ("btusb" OR "Bluetooth")