CVE-2025-38687
📋 TL;DR
A race condition vulnerability in the Linux kernel's comedi subsystem allows use-after-free when polling operations overlap with device detachment. This can lead to kernel memory corruption or system crashes. Systems using comedi devices for data acquisition or industrial control 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 →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 leading to denial of service, potential privilege escalation if combined with other vulnerabilities.
Likely Case
System instability, kernel crashes, or denial of service affecting comedi device functionality.
If Mitigated
Minimal impact if comedi devices are not in use or proper access controls prevent unauthorized COMEDI_DEVCONFIG ioctl calls.
🎯 Exploit Status
Requires local access and ability to trigger COMEDI_DEVCONFIG ioctl while polling operations are active.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Multiple stable kernel versions with commit hashes provided in references
Vendor Advisory: https://git.kernel.org/stable/c/017198079551a2a5cf61eae966af3c4b145e1f3b
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable comedi module
LinuxPrevent loading of comedi kernel module if not required
echo 'blacklist comedi' >> /etc/modprobe.d/blacklist.conf
rmmod comedi
Restrict comedi device access
LinuxLimit access to comedi devices to authorized users only
chmod 600 /dev/comedi*
setfacl -m u:username:rw /dev/comedi*
🧯 If You Can't Patch
- Disable comedi kernel module if not required for system functionality
- Implement strict access controls to prevent unauthorized users from accessing comedi devices
🔍 How to Verify
Check if Vulnerable:
Check if comedi module is loaded: lsmod | grep comedi. Check kernel version against patched versions.Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes fix commits or is newer than patched versions. Check /proc/version or uname -r.📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages
- System crashes related to comedi
- Use-after-free warnings in kernel logs
Network Indicators:
- None - local vulnerability only
SIEM Query:
source="kernel" AND ("comedi" OR "use-after-free" OR "general protection fault")🔗 References
- https://git.kernel.org/stable/c/017198079551a2a5cf61eae966af3c4b145e1f3b
- https://git.kernel.org/stable/c/0f989f9d05492028afd2bded4b42023c57d8a76e
- https://git.kernel.org/stable/c/35b6fc51c666fc96355be5cd633ed0fe4ccf68b2
- https://git.kernel.org/stable/c/5724e82df4f9a4be62908362c97d522d25de75dd
- https://git.kernel.org/stable/c/5c4a2ffcbd052c69bbf4680677d4c4eaa5a252d4
- https://git.kernel.org/stable/c/71ca60d2e631cf9c63bcbc7017961c61ff04e419
- https://git.kernel.org/stable/c/cd4286123d6948ff638ea9cd5818ae4796d5d252
- https://git.kernel.org/stable/c/d85fac8729c9acfd72368faff1d576ec585e5c8f
- https://git.kernel.org/stable/c/fe67122ba781df44a1a9716eb1dfd751321ab512
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
