CVE-2025-21717
📋 TL;DR
This vulnerability in the Linux kernel's mlx5e network driver allows out-of-bounds memory access when performing ethtool or netlink operations on systems with CPUs beyond MAX_NUMNODES. The missing cpu_to_node conversion causes kernel panic and system crashes. Systems using Mellanox network adapters with affected kernel versions are vulnerable.
💻 Affected Systems
- Linux kernel mlx5e 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash and denial of service, potentially causing data loss or service disruption.
Likely Case
System crash when performing network configuration operations via ethtool or netlink on affected hardware.
If Mitigated
No impact if systems don't use affected Mellanox hardware or have patched kernels.
🎯 Exploit Status
Requires ability to trigger specific network operations on affected hardware; not remotely exploitable.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits 979284535aaf12a287a2f43d9d5dfcbdc1dc4cac or a275db45b4161d01716559dd7557db9ea0450952
Vendor Advisory: https://git.kernel.org/stable/c/979284535aaf12a287a2f43d9d5dfcbdc1dc4cac
Restart Required: No
Instructions:
1. Update Linux kernel to version containing the fix commit. 2. For distributions: apply kernel security updates from your vendor. 3. Rebuild kernel if compiling from source.
🔧 Temporary Workarounds
Avoid network configuration operations
allPrevent triggering the vulnerable code path by avoiding ethtool and netlink operations that call mlx5e_open.
🧯 If You Can't Patch
- Restrict access to network configuration tools (ethtool, ip, etc.) to trusted administrators only.
- Monitor for kernel panic logs and have incident response procedures ready for potential crashes.
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if mlx5_core driver is loaded: 'uname -r' and 'lsmod | grep mlx5'Check Version:
uname -rVerify Fix Applied:
Verify kernel version is updated beyond vulnerable range and check for presence of cpu_to_node in mlx5e_open_xdpredirect_sq function.📡 Detection & Monitoring
Log Indicators:
- Kernel panic messages
- OOB access errors in dmesg
- 'BUG: unable to handle page fault' logs
Network Indicators:
- Sudden network interface failures on Mellanox hardware
SIEM Query:
source="kernel" AND ("page fault" OR "OOB" OR "mlx5e_open" OR "panic")