untrusted comment: verify with openbsd-70-base.pub
RWR3KL+gSr4QZwZ7t6C9cOWxlyVBzym720e+gV6Abx4JoduDw3YTQs4csDBbRhqN3qrvRlAlsUV7yOc/b4YgizjZZTngHx/0mwM=

OpenBSD 7.0 errata 014, February 21, 2022:

More than 7 nameservers in an IPv6 router advertisement could crash slaacd.

Apply by doing:
    signify -Vep /etc/signify/openbsd-70-base.pub -x 014_slaacd.patch.sig \
        -m - | (cd /usr/src && patch -p0)

And then rebuild and install slaacd:
    cd /usr/src/sbin/slaacd
    make obj
    make
    make install

Index: sbin/slaacd/engine.c
===================================================================
RCS file: /cvs/src/sbin/slaacd/engine.c,v
diff -u -p -u -r1.74 engine.c
--- sbin/slaacd/engine.c	22 Jul 2021 15:32:51 -0000	1.74
+++ sbin/slaacd/engine.c	20 Feb 2022 16:13:58 -0000
@@ -2238,7 +2238,7 @@ gen_rdns_proposal(struct slaacd_iface *i
 	rdns_proposal->rdns_lifetime = ra->rdns_lifetime;
 	LIST_FOREACH(rdns, &ra->rdns_servers, entries) {
 		memcpy(&rdns_proposal->rdns[rdns_proposal->rdns_count++],
-		    &rdns->rdns, sizeof(struct sockaddr_in6));
+		    &rdns->rdns, sizeof(struct in6_addr));
 		if (rdns_proposal->rdns_count == MAX_RDNS_COUNT)
 			break;
 	}