diff --git a/example/reader_util.c b/example/reader_util.c
index 00dc7f25173..3c49563edb6 100644
--- a/example/reader_util.c
+++ b/example/reader_util.c
@@ -116,14 +116,14 @@ u_int16_t max_pattern_len = 8;
 
 /* *********************************************************** */
 
-void ndpi_analyze_payload(struct ndpi_flow_info *flow,
-			  u_int8_t src_to_dst_direction,
-			  u_int8_t *payload,
-			  u_int16_t payload_len,
-			  u_int32_t packet_id) {
-  struct payload_stats *ret;
-  struct flow_id_stats *f;
-  struct packet_id_stats *p;
+int ndpi_analyze_payload(struct ndpi_flow_info *flow,
+			 u_int8_t src_to_dst_direction,
+			 u_int8_t *payload,
+			 u_int16_t payload_len,
+			 u_int32_t packet_id) {
+  struct payload_stats *ret, *ret_found;
+  struct flow_id_stats *f, *f_found;
+  struct packet_id_stats *p, *p_found;
 
 #ifdef DEBUG_PAYLOAD
   u_int16_t i;
@@ -135,11 +135,11 @@ void ndpi_analyze_payload(struct ndpi_flow_info *flow,
   HASH_FIND(hh, pstats, payload, payload_len, ret);
   if(ret == NULL) {
     if((ret = (struct payload_stats*)ndpi_calloc(1, sizeof(struct payload_stats))) == NULL)
-      return; /* OOM */
+      return -1; /* OOM */
 
     if((ret->pattern = (u_int8_t*)ndpi_malloc(payload_len)) == NULL) {
       ndpi_free(ret);
-      return;
+      return -1;
     }
 
     memcpy(ret->pattern, payload, payload_len);
@@ -148,6 +148,13 @@ void ndpi_analyze_payload(struct ndpi_flow_info *flow,
 
     HASH_ADD(hh, pstats, pattern[0], payload_len, ret);
 
+    HASH_FIND(hh, pstats, payload, payload_len, ret_found);
+    if(ret_found == NULL) { /* The insertion failed (because of a memory allocation error) */
+      ndpi_free(ret->pattern);
+      ndpi_free(ret);
+      return -1;
+    }
+
 #ifdef DEBUG_PAYLOAD
     printf("Added element [total: %u]\n", HASH_COUNT(pstats));
 #endif
@@ -159,20 +166,32 @@ void ndpi_analyze_payload(struct ndpi_flow_info *flow,
   HASH_FIND_INT(ret->flows, &flow->flow_id, f);
   if(f == NULL) {
     if((f = (struct flow_id_stats*)ndpi_calloc(1, sizeof(struct flow_id_stats))) == NULL)
-      return; /* OOM */
+      return -1; /* OOM */
 
     f->flow_id = flow->flow_id;
     HASH_ADD_INT(ret->flows, flow_id, f);
+
+    HASH_FIND_INT(ret->flows, &flow->flow_id, f_found);
+    if(f_found == NULL) { /* The insertion failed (because of a memory allocation error) */
+      ndpi_free(f);
+      return -1;
+    }
   }
 
   HASH_FIND_INT(ret->packets, &packet_id, p);
   if(p == NULL) {
     if((p = (struct packet_id_stats*)ndpi_calloc(1, sizeof(struct packet_id_stats))) == NULL)
-      return; /* OOM */
+      return -1; /* OOM */
     p->packet_id = packet_id;
 
     HASH_ADD_INT(ret->packets, packet_id, p);
+
+    HASH_FIND_INT(ret->packets, &packet_id, p_found);
+    if(p_found == NULL) { /* The insertion failed (because of a memory allocation error) */
+      ndpi_free(p);
+    }
   }
+  return 0;
 }
 
 /* *********************************************************** */
@@ -199,7 +218,12 @@ void ndpi_payload_analyzer(struct ndpi_flow_info *flow,
   for(i=0; i<scan_len; i++) {
     for(j=min_pattern_len; j <= max_pattern_len; j++) {
       if((i+j) < payload_len) {
-	ndpi_analyze_payload(flow, src_to_dst_direction, &payload[i], j, packet_id);
+	if(ndpi_analyze_payload(flow, src_to_dst_direction, &payload[i], j, packet_id) == -1) {
+#ifndef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
+          /* Avoid too much logging while fuzzing */
+          LOG(NDPI_LOG_ERROR, "Error ndpi_analyze_payload (allocation failure)\n");
+#endif
+	}
       }
     }
   }
@@ -960,6 +984,12 @@ static struct ndpi_flow_info *get_ndpi_flow_info(struct ndpi_workflow * workflow
       if(enable_flow_stats) {
         newflow->entropy = ndpi_calloc(1, sizeof(struct ndpi_entropy));
         newflow->last_entropy = ndpi_calloc(1, sizeof(struct ndpi_entropy));
+        if(!newflow->entropy || !newflow->last_entropy) {
+          ndpi_tdelete(newflow, &workflow->ndpi_flows_root[idx], ndpi_workflow_node_cmp);
+          ndpi_flow_info_free_data(newflow);
+          ndpi_free(newflow);
+          return(NULL);
+        }
         newflow->entropy->src2dst_pkt_len[newflow->entropy->src2dst_pkt_count] = l4_data_len;
         newflow->entropy->src2dst_pkt_time[newflow->entropy->src2dst_pkt_count] = when;
         if(newflow->entropy->src2dst_pkt_count == 0) {
diff --git a/fuzz/fuzz_ds_ahocorasick.cpp b/fuzz/fuzz_ds_ahocorasick.cpp
index 5297236e31f..e02744e52a9 100644
--- a/fuzz/fuzz_ds_ahocorasick.cpp
+++ b/fuzz/fuzz_ds_ahocorasick.cpp
@@ -133,7 +133,8 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 
   f = fopen("/dev/null", "w");
   ac_automata_dump(a, f);
-  fclose(f);
+  if (f)
+    fclose(f);
 
   ac_automata_get_stats(a, &stats);
 
diff --git a/fuzz/fuzz_libinjection.c b/fuzz/fuzz_libinjection.c
index c878fe823b2..f614a62e12f 100644
--- a/fuzz/fuzz_libinjection.c
+++ b/fuzz/fuzz_libinjection.c
@@ -12,6 +12,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
   /* Libinjection: it wants null-terminated string */
 
   query = malloc(size + 1);
+  if (!query)
+    return 0;
   memcpy(query, data, size);
   query[size] = '\0';
 
diff --git a/fuzz/fuzz_process_packet.c b/fuzz/fuzz_process_packet.c
index dcd15c99e37..3f0694cf988 100644
--- a/fuzz/fuzz_process_packet.c
+++ b/fuzz/fuzz_process_packet.c
@@ -5,6 +5,7 @@
 #include <stdio.h>
 
 struct ndpi_detection_module_struct *ndpi_info_mod = NULL;
+struct ndpi_flow_struct ndpi_flow;
 static ndpi_serializer json_serializer = {};
 static ndpi_serializer csv_serializer = {};
 
@@ -18,24 +19,23 @@ int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
     ndpi_init_serializer(&csv_serializer, ndpi_serialization_format_csv);
   }
 
-  struct ndpi_flow_struct *ndpi_flow = ndpi_flow_malloc(SIZEOF_FLOW_STRUCT);
-  memset(ndpi_flow, 0, SIZEOF_FLOW_STRUCT);
+  memset(&ndpi_flow, 0, SIZEOF_FLOW_STRUCT);
   ndpi_protocol detected_protocol =
-    ndpi_detection_process_packet(ndpi_info_mod, ndpi_flow, Data, Size, 0, NULL);
+    ndpi_detection_process_packet(ndpi_info_mod, &ndpi_flow, Data, Size, 0, NULL);
   ndpi_protocol guessed_protocol =
-    ndpi_detection_giveup(ndpi_info_mod, ndpi_flow, 1, &protocol_was_guessed);
+    ndpi_detection_giveup(ndpi_info_mod, &ndpi_flow, 1, &protocol_was_guessed);
 
   ndpi_reset_serializer(&json_serializer);
   ndpi_reset_serializer(&csv_serializer);
   if (protocol_was_guessed == 0)
   {
-    ndpi_dpi2json(ndpi_info_mod, ndpi_flow, detected_protocol, &json_serializer);
-    ndpi_dpi2json(ndpi_info_mod, ndpi_flow, detected_protocol, &csv_serializer);
+    ndpi_dpi2json(ndpi_info_mod, &ndpi_flow, detected_protocol, &json_serializer);
+    ndpi_dpi2json(ndpi_info_mod, &ndpi_flow, detected_protocol, &csv_serializer);
   } else {
-    ndpi_dpi2json(ndpi_info_mod, ndpi_flow, guessed_protocol, &json_serializer);
-    ndpi_dpi2json(ndpi_info_mod, ndpi_flow, guessed_protocol, &csv_serializer);
+    ndpi_dpi2json(ndpi_info_mod, &ndpi_flow, guessed_protocol, &json_serializer);
+    ndpi_dpi2json(ndpi_info_mod, &ndpi_flow, guessed_protocol, &csv_serializer);
   }
-  ndpi_free_flow(ndpi_flow);
+  ndpi_free_flow_data(&ndpi_flow);
 
   return 0;
 }
diff --git a/src/lib/ndpi_main.c b/src/lib/ndpi_main.c
index 9776b0b02b5..7a5de852f2f 100644
--- a/src/lib/ndpi_main.c
+++ b/src/lib/ndpi_main.c
@@ -2509,6 +2509,9 @@ static int ndpi_add_host_ip_subprotocol(struct ndpi_detection_module_struct *ndp
   u_int16_t port = 0; /* Format ip:8.248.73.247:443 */
   char *double_column;
 
+  if(!ndpi_str->protocols_ptree)
+    return(-1);
+
   if(ptr) {
     ptr[0] = '\0';
     ptr++;
@@ -3674,6 +3677,9 @@ int ndpi_add_ip_risk_mask(struct ndpi_detection_module_struct *ndpi_str,
 			  char *ip, ndpi_risk mask) {
   char *saveptr, *addr = strtok_r(ip, "/", &saveptr);
 
+  if(!ndpi_str->ip_risk_mask_ptree)
+    return(-3);
+
   if(addr) {
     char *cidr = strtok_r(NULL, "\n", &saveptr);
     struct in_addr pin;
@@ -6483,6 +6489,9 @@ int ndpi_load_ip_category(struct ndpi_detection_module_struct *ndpi_str,
   char *ptr;
   char ipbuf[64];
 
+  if(!ndpi_str->custom_categories.ipAddresses_shadow)
+    return(-1);
+
   strncpy(ipbuf, ip_address_and_mask, sizeof(ipbuf));
   ipbuf[sizeof(ipbuf) - 1] = '\0';
 
@@ -6618,7 +6627,9 @@ int ndpi_fill_ip_protocol_category(struct ndpi_detection_module_struct *ndpi_str
 
   ret->custom_category_userdata = NULL;
 
-  if(ndpi_str->custom_categories.categories_loaded) {
+  if(ndpi_str->custom_categories.categories_loaded &&
+     ndpi_str->custom_categories.ipAddresses) {
+
     ndpi_prefix_t prefix;
     ndpi_patricia_node_t *node;
 
diff --git a/src/lib/ndpi_utils.c b/src/lib/ndpi_utils.c
index dfdca923acc..0199d6424f9 100644
--- a/src/lib/ndpi_utils.c
+++ b/src/lib/ndpi_utils.c
@@ -2288,6 +2288,7 @@ int ndpi_hash_add_entry(ndpi_str_hash **h, char *key, u_int8_t key_len, void *va
 {
   struct ndpi_str_hash_private **h_priv = (struct ndpi_str_hash_private **)h;
   struct ndpi_str_hash_private *new = ndpi_calloc(1, sizeof(*new));
+  struct ndpi_str_hash_private *found;
   unsigned int hash_value;
 
   if (new == NULL)
@@ -2299,6 +2300,14 @@ int ndpi_hash_add_entry(ndpi_str_hash **h, char *key, u_int8_t key_len, void *va
   new->hash = hash_value;
   new->value = value;
   HASH_ADD_INT(*h_priv, hash, new);
+
+  HASH_FIND_INT(*h_priv, &hash_value, found);
+  if (found == NULL) /* The insertion failed (because of a memory allocation error) */
+  {
+    ndpi_free(new);
+    return 1;
+  }
+
   return 0;
 }
 
diff --git a/src/lib/third_party/include/uthash.h b/src/lib/third_party/include/uthash.h
index b7dfe4d3b3c..7cf305d417b 100644
--- a/src/lib/third_party/include/uthash.h
+++ b/src/lib/third_party/include/uthash.h
@@ -101,7 +101,7 @@ do {
 #endif
 
 #ifndef HASH_NONFATAL_OOM
-#define HASH_NONFATAL_OOM 0
+#define HASH_NONFATAL_OOM 1
 #endif
 
 #if HASH_NONFATAL_OOM