diff --git a/.changelog/12277.txt b/.changelog/12277.txt
new file mode 100644
index 000000000..7435bbb37
--- /dev/null
+++ b/.changelog/12277.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+config-entry: fix a panic when creating an ingress gateway config-entry and a proxy service instance, where both provided the same upstream and downstream mapping.
+```
diff --git a/agent/consul/state/catalog.go b/agent/consul/state/catalog.go
index 90657d841..7ceb98caf 100644
--- a/agent/consul/state/catalog.go
+++ b/agent/consul/state/catalog.go
@@ -4016,6 +4016,7 @@ func insertGatewayServiceTopologyMapping(tx WriteTxn, idx uint64, gs *structs.Ga
 	mapping := upstreamDownstream{
 		Upstream:   gs.Service,
 		Downstream: gs.Gateway,
+		Refs:       make(map[string]struct{}),
 		RaftIndex:  gs.RaftIndex,
 	}
 	if err := tx.Insert(tableMeshTopology, &mapping); err != nil {