In the Linux kernel, the following vulnerability has been resolved:
xen-netback: defer xenvif_mcast_addr_list_free()
In order for the function to legitimately avoid locking/RCU, it needs to
run after all TX/RX processing has finished/stopped: Lookups happen from
xenvif_start_xmit(), while adds/removes happen from xenvif_tx_action()
(called out of xenvif_poll()).
Move the call out of xenvif_disconnect_data() (the call to the function
from connect()'s error path doesn't require any cleaning up there), and
put it past the synchronization point in backend_disconnect().
This is XSA-527 / CVE-2026-100081.