CVE-2025-39834
📋 TL;DR
A memory leak vulnerability exists in the Linux kernel's mlx5 hardware steering (HWS) component when invalid stc_type values are provided. This affects systems using Mellanox/NVIDIA network adapters with the mlx5 driver. The vulnerability could lead to resource exhaustion over time.
💻 Affected Systems
- Linux kernel with mlx5 driver
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Sustained exploitation could cause kernel memory exhaustion, leading to system instability, crashes, or denial of service.
Likely Case
Gradual memory consumption increase over time, potentially affecting system performance and reliability.
If Mitigated
Minimal impact with proper monitoring and resource limits in place.
🎯 Exploit Status
Requires ability to trigger specific error conditions in mlx5 HWS component
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel branches (commits 051fd8576a2e4e95d5870c5c9f8679c5b16882e4 and a630f83592cdad1253523a1b760cfe78fef6cd9c)
Vendor Advisory: https://git.kernel.org/stable/c/051fd8576a2e4e95d5870c5c9f8679c5b16882e4
Restart Required: No
Instructions:
1. Update to patched kernel version from your distribution vendor. 2. Apply kernel patches if building from source. 3. Reboot to load new kernel.
🔧 Temporary Workarounds
Disable mlx5 HWS feature
LinuxDisable hardware steering feature if not required
echo 0 > /sys/class/net/<interface>/device/sriov_numvfs
Note: This disables SR-IOV functionality
🧯 If You Can't Patch
- Implement kernel memory monitoring and alerting
- Restrict access to systems using mlx5 adapters to trusted users only
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if mlx5 driver is loaded: lsmod | grep mlx5Check Version:
uname -rVerify Fix Applied:
Verify kernel version includes the fix commits or is newer than patched version📡 Detection & Monitoring
Log Indicators:
- Kernel oom-killer messages
- System memory exhaustion warnings
- mlx5 driver error messages
Network Indicators:
- Unusual network performance degradation on mlx5 interfaces
SIEM Query:
source="kernel" AND ("oom" OR "memory" OR "mlx5")