diff --git a/src/dbSta/include/db_sta/dbNetwork.hh b/src/dbSta/include/db_sta/dbNetwork.hh
index 9d2fbf19b26..9c1998c938c 100644
--- a/src/dbSta/include/db_sta/dbNetwork.hh
+++ b/src/dbSta/include/db_sta/dbNetwork.hh
@@ -360,7 +360,10 @@ class dbNetwork : public ConcreteNetwork
 
   // Return the highest net above the given net.
   // - If the net is a flat net, return it.
-  // - If the net is a hier net, return the modnet in the highest hierarchy.
+  // - If the net is a hier net (dbModNet), return the associated flat dbNet.
+  // This ensures parasitic externality checks in ensureParasiticNode work
+  // correctly: net_ is always a flat net, so the comparison net != net_
+  // must also operate on flat nets.
   Net* highestNetAbove(Net* net) const override;
 
   ////////////////////////////////////////////////////////////////
diff --git a/src/dbSta/src/dbNetwork.cc b/src/dbSta/src/dbNetwork.cc
index 4a104e6754c..b62c26d8df7 100644
--- a/src/dbSta/src/dbNetwork.cc
+++ b/src/dbSta/src/dbNetwork.cc
@@ -2016,9 +2016,18 @@ void dbNetwork::visitConnectedPins(const Net* net,
   }
 }
 
+// Caution:
+//- Network::highestConnectedNet(Net *net) retrieves the highest hierarchical
+// net connected to the given net.
+// - But `dbNetwork::highestConnectedNet(Net* net)` retrieves the corresponding
+// flat net for the given net.
+// - It behaves differently to cope with the issue 9724.
+// - This redefinition may cause another issue later when
+// `Network::highestConnectedNet(Net *net)` is used elsewhere.
 const Net* dbNetwork::highestConnectedNet(Net* net) const
 {
-  return net;
+  const Net* flat = findFlatNet(net);
+  return flat ? flat : net;
 }
 
 ////////////////////////////////////////////////////////////////
@@ -5198,11 +5207,15 @@ Net* dbNetwork::highestNetAbove(Net* net) const
   }
 
   if (modnet) {
+    // Return the flat net associated with this mod net.
+    // Parasitic externality checks in
+    // ConcreteParasiticNetwork::ensureParasiticNode compare against net_ which
+    // is always a flat net (set via makeParasiticNetwork). Returning the
+    // highest mod net causes all pin nodes on hierarchically-connected nets to
+    // compare unequal to net_ and be incorrectly marked as external, making
+    // node_count_ = 0 and crashing PRIMA in measureThresholds.
     if (dbNet* related_dbnet = modnet->findRelatedNet()) {
-      if (odb::dbModNet* highest_modnet
-          = related_dbnet->findModNetInHighestHier()) {
-        return dbToSta(highest_modnet);  // Found the highest modnet
-      }
+      return dbToSta(related_dbnet);
     }
   }
 
diff --git a/src/dbSta/test/cpp/TestDbSta.cc b/src/dbSta/test/cpp/TestDbSta.cc
index d752d0421b1..f1c9c549d34 100644
--- a/src/dbSta/test/cpp/TestDbSta.cc
+++ b/src/dbSta/test/cpp/TestDbSta.cc
@@ -77,9 +77,11 @@ TEST_F(TestDbSta, TestHierarchyConnectivity)
   ASSERT_NE(modnet_out2, nullptr);
   Net* sta_modnet_out2 = db_network_->dbToSta(modnet_out2);
   ASSERT_NE(sta_modnet_out2, nullptr);
+  // highestNetAbove on a mod net now returns the associated flat dbNet, not the
+  // highest mod net, so that parasitic externality checks work correctly.
   Net* sta_highest_modnet_out
       = db_network_->highestNetAbove(sta_modnet_mod_out);
-  ASSERT_EQ(sta_highest_modnet_out, sta_modnet_out2);
+  ASSERT_EQ(sta_highest_modnet_out, sta_dbnet_out2);
 
   // Check get_ports -of_object Net*
   NetTermIterator* term_iter = db_network_->termIterator(sta_dbnet_out2);
diff --git a/src/sta b/src/sta
index ffda41536fe..41ad5c62b8f 160000
--- a/src/sta
+++ b/src/sta
@@ -1 +1 @@
-Subproject commit ffda41536fe1cff4a3a9eed7caf9f810f63234e0
+Subproject commit 41ad5c62b8f6f2596d9b1983255c0928537bdd31