diff --git a/CHANGES b/CHANGES
index db1c491604..bb7b6c4957 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+4793.	[bug]		nsupdate -[46] could overflow the array of server
+			addresses. [RT #46402]
+
 4792.	[bug]		Fix map file header correctness check. [RT #38418]
 
 4791.	[doc]		Fixed outdated documentation about export libraries.
diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index c922cf9765..5162fb31ed 100644
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@@ -944,16 +944,21 @@ setup_system(void) {
 			case AF_INET:
 				if (have_ipv4) {
 					sa->type.sin.sin_port = htons(dnsport);
+				} else {
+					continue;
 				}
 				break;
 			case AF_INET6:
 				if (have_ipv6) {
 					sa->type.sin6.sin6_port = htons(dnsport);
+				} else {
+					continue;
 				}
 				break;
 			default:
 				fatal("bad family");
 			}
+			INSIST(i < ns_alloc);
 			servers[i++] = *sa;
 		}
 	}