Critical Vulnerability in Linux Kernel: MDIO Bus PM Operations
Summary
DEBIAN-CVE-2025-37945: In the Linux kernel, the following vulnerability has been resolved: net: phy: allow MDIO bus PM ops to start/stop state machine for phylink-controlled PHY DSA has 2 kinds of drivers: 1. Affects linux versions < 6.12.25-1. Fixed in 6.12.25-1. How to fix ↓
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Background
The Linux kernel is a core component of the operating system that manages hardware and system resources. It provides essential services for all applications and is known for its stability and performance. This vulnerability affects the Linux kernel versions in Debian 13 and 14, specifically related to the management of PHY (Physical Layer) devices in networking. The issue arises from improper handling of power management operations, which can lead to unexpected behavior in network devices.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the handling of power management operations for MDIO bus-controlled PHY devices. The issue stems from the failure to stop the PHY state machine during suspend operations, leading to potential warnings and undefined behavior when resuming. This can affect any MAC driver using phylink and MDIO-bus-managed PHY PM operations, resulting in network instability and crashes. The vulnerability is particularly concerning for drivers that do not implement MAC-managed power management, as they may not handle PHY state transitions correctly.
How To Fix
Minimum fixed version
6.12.25-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, users can manually manage the PHY state transitions by ensuring that the PHY state machine is stopped before entering suspend mode. This can be done by invoking the phy_stop_machine() function in the driver code before suspending the device.
Conclusion
The identified vulnerability in the Linux kernel regarding MDIO bus power management operations poses significant risks to network stability. It is crucial for users to update their systems to the patched version to mitigate these risks. Additionally, utilizing tools like Vulert can help in monitoring and managing vulnerabilities effectively.
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FAQ
The vulnerability can lead to network instability, crashes, and unexpected behavior in devices that rely on MDIO bus-controlled PHY operations.
You can use the Vulert platform to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected.
Yes, a patch is available in the form of the Linux package version 6.12.25-1. Updating to this version will resolve the vulnerability.
If immediate updates are not possible, consider implementing the workaround by managing PHY state transitions manually in your driver code.
Detailed information can be found in the official Debian CVE database at https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-37945.json.
References
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