CVE-2025-21923
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's HID steam driver allows attackers to potentially execute arbitrary code or cause system crashes when detaching Steam controller devices. This affects Linux systems with Steam controller support enabled. Attackers need physical access or ability to connect USB devices to exploit this vulnerability.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation to kernel-level code execution, potentially leading to full system compromise.
Likely Case
Kernel panic or system crash causing denial of service.
If Mitigated
No impact if proper access controls prevent unauthorized USB device connections.
🎯 Exploit Status
Exploitation requires physical USB access or ability to connect devices. No public exploits known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in stable kernel versions via commits referenced in CVE
Vendor Advisory: https://git.kernel.org/stable/c/026714ec7546de741826324a6a1914c91024d06c
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from distribution vendor. 2. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable hid-steam module
linuxPrevent loading of vulnerable hid-steam driver
echo 'blacklist hid-steam' >> /etc/modprobe.d/blacklist.conf
rmmod hid-steam
Restrict USB device connections
linuxPrevent unauthorized USB device connections via udev rules
echo 'ACTION=="add", SUBSYSTEM=="usb", ATTR{idVendor}=="28de", ATTR{idProduct}=="1102", RUN+="/bin/false"' >> /etc/udev/rules.d/99-block-steam.rules
udevadm control --reload-rules
🧯 If You Can't Patch
- Restrict physical access to USB ports
- Implement USB device whitelisting policies
🔍 How to Verify
Check if Vulnerable:
Check if hid-steam module is loaded: lsmod | grep hid_steamCheck Version:
uname -rVerify Fix Applied:
Check kernel version against patched versions from distribution vendor📡 Detection & Monitoring
Log Indicators:
- Kernel oops messages in dmesg
- System crashes when disconnecting USB devices
Network Indicators:
- None - local vulnerability only
SIEM Query:
Search for kernel panic or oops events in system logs