Linux Kernel Vulnerability Affecting Macsec Feature Synchronization

CVE-2025-39874

What is CVE-2025-39874?

A vulnerability exists in the Linux kernel concerning the synchronization of features between upper and lower network devices when using macsec. Specifically, the issue emerges when lower features do not align with upper features during the use of ETHTOOL_SFEATURES, leading to potential deadlock situations. This flaw is exacerbated by the elimination of lock/unlock operations when features are already synced, which could hinder proper updates to lower device configurations during macsec link operations. The implications could affect network reliability and functionality, highlighting the importance of appropriate feature management in kernel network drivers.

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