CVE-2026-16515 ICMPv6 error messages sent for multicast-destined packets and non-unique source addresses enable network amplification in Zephyr's IPv6 stack

neticmpv6senderror in subsys/net/ip/icmpv6.c implemented only one of the three RFC 4443 section 2.4 suppression rules do not answer an ICMPv6 error with an ICMPv6 error. It did not check whether the triggering packet's source address identifies a single node rule e.6 or whether the packet was sen...