In the Linux kernel, the following vulnerability has been resolved: macsec: initialize SecY before registering the netdevice Creating a MACsec… (CVE-2026-98929)

The Linux kernel MACsec driver had a vulnerability where creating a MACsec device with MAC offload over an LRO-capable lower device triggered warnings in rtmsg_ifinfo_build_skb() due to uninitialized SecY attributes during network device registration. This was caused by register_netdevice() invoking inetdev_init(), which disables LRO and sends NETDEV_FEAT_CHANGE notifications before SecY was initialized, leading to macsec_fill_info() returning an error and triggering warnings. The fix initializes SecY and applies new-link attributes before registration, moves MAC address inheritance to macsec_newlink(), and adjusts allocation of per-CPU statistics and metadata destination to prevent partial allocation failures.

The vulnerability caused kernel warnings and could lead to notifications reporting uninitialized SecY attributes, including the SCI, during MACsec device registration. This could affect system stability or reliability of network device state reporting but does not indicate direct exploitation or security compromise based on the provided data.

A fix has been implemented that initializes the SecY and applies new-link attributes before network device registration, preventing the warnings and uninitialized attribute reporting. Users should update to the fixed Linux kernel version once available. No additional mitigation actions are indicated.