A Linux kernel bug in the bcmgenet network driver caused the driver to clear its hardware filter list every time an interface was opened. The clearing operation removes all user‑configured flow rules, which are normally set with ethtool. As a result, any custom packet filtering rules configured on the interface are silently lost whenever the interface is restarted, leaving the system without the intended hardware‑level filtering.

Systems that run Linux kernels containing the unpatched bcmgenet driver are affected. The errata does not list specific kernel versions, but the issue applies to any kernel in which bcmgenet_hfb_init() is called on each interface activation. This includes older kernel releases still used in some distributions that have not incorporated the upstream commit restoring the filters on open.

The EPSS score is less than 1 %, indicating a very low likelihood of exploitation. The vulnerability is not included in the CISA KEV catalog, and the CVSS score is 5.5. It does not involve privilege escalation or remote code execution, but it can undermine a system’s network traffic filtering capabilities. An attacker who can restart a network interface on a privileged host can cause custom hardware filters to disappear, weakening firewall or switch‑level controls at the host level.