diff --git a/crypto/x509v3/pcy_local.h b/crypto/x509v3/pcy_local.h
index 5daf78de45850e5a8b962f2ba145fda1e78a9a6b..344aa067659cd357866fb860a327d0f54114bef8 100644
--- a/crypto/x509v3/pcy_local.h
+++ b/crypto/x509v3/pcy_local.h
@@ -111,6 +111,11 @@ struct X509_POLICY_LEVEL_st {
 };
 
 struct X509_POLICY_TREE_st {
+    /* The number of nodes in the tree */
+    size_t node_count;
+    /* The maximum number of nodes in the tree */
+    size_t node_maximum;
+
     /* This is the tree 'level' data */
     X509_POLICY_LEVEL *levels;
     int nlevel;
@@ -159,7 +164,8 @@ X509_POLICY_NODE *tree_find_sk(STACK_OF(X509_POLICY_NODE) *sk,
 X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
                                  X509_POLICY_DATA *data,
                                  X509_POLICY_NODE *parent,
-                                 X509_POLICY_TREE *tree);
+                                 X509_POLICY_TREE *tree,
+                                 int extra_data);
 void policy_node_free(X509_POLICY_NODE *node);
 int policy_node_match(const X509_POLICY_LEVEL *lvl,
                       const X509_POLICY_NODE *node, const ASN1_OBJECT *oid);
diff --git a/crypto/x509v3/pcy_node.c b/crypto/x509v3/pcy_node.c
index e2d7b153223636a56efcf0cbd568892e38ad0a7a..d574fb9d665dcfbce5f2ab613bdb61875d7aa982 100644
--- a/crypto/x509v3/pcy_node.c
+++ b/crypto/x509v3/pcy_node.c
@@ -59,10 +59,15 @@ X509_POLICY_NODE *level_find_node(const X509_POLICY_LEVEL *level,
 X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
                                  X509_POLICY_DATA *data,
                                  X509_POLICY_NODE *parent,
-                                 X509_POLICY_TREE *tree)
+                                 X509_POLICY_TREE *tree,
+                                 int extra_data)
 {
     X509_POLICY_NODE *node;
 
+    /* Verify that the tree isn't too large.  This mitigates CVE-2023-0464 */
+    if (tree->node_maximum > 0 && tree->node_count >= tree->node_maximum)
+        return NULL;
+
     node = OPENSSL_zalloc(sizeof(*node));
     if (node == NULL) {
         X509V3err(X509V3_F_LEVEL_ADD_NODE, ERR_R_MALLOC_FAILURE);
@@ -70,7 +75,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
     }
     node->data = data;
     node->parent = parent;
-    if (level) {
+    if (level != NULL) {
         if (OBJ_obj2nid(data->valid_policy) == NID_any_policy) {
             if (level->anyPolicy)
                 goto node_error;
@@ -90,7 +95,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
         }
     }
 
-    if (tree) {
+    if (extra_data) {
         if (tree->extra_data == NULL)
             tree->extra_data = sk_X509_POLICY_DATA_new_null();
         if (tree->extra_data == NULL){
@@ -103,6 +108,7 @@ X509_POLICY_NODE *level_add_node(X509_POLICY_LEVEL *level,
         }
     }
 
+    tree->node_count++;
     if (parent)
         parent->nchild++;
 
diff --git a/crypto/x509v3/pcy_tree.c b/crypto/x509v3/pcy_tree.c
index 6e8322cbc5e38c9711538e58cb0be2b0d235e8a6..6c7fd35405000d0c1da01d3130b1ef7e71231522 100644
--- a/crypto/x509v3/pcy_tree.c
+++ b/crypto/x509v3/pcy_tree.c
@@ -13,6 +13,18 @@
 
 #include "pcy_local.h"
 
+/*
+ * If the maximum number of nodes in the policy tree isn't defined, set it to
+ * a generous default of 1000 nodes.
+ *
+ * Defining this to be zero means unlimited policy tree growth which opens the
+ * door on CVE-2023-0464.
+ */
+
+#ifndef OPENSSL_POLICY_TREE_NODES_MAX
+# define OPENSSL_POLICY_TREE_NODES_MAX 1000
+#endif
+
 /*
  * Enable this to print out the complete policy tree at various point during
  * evaluation.
@@ -168,6 +180,9 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
         return X509_PCY_TREE_INTERNAL;
     }
 
+    /* Limit the growth of the tree to mitigate CVE-2023-0464 */
+    tree->node_maximum = OPENSSL_POLICY_TREE_NODES_MAX;
+
     /*
      * http://tools.ietf.org/html/rfc5280#section-6.1.2, figure 3.
      *
@@ -184,7 +199,7 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
     level = tree->levels;
     if ((data = policy_data_new(NULL, OBJ_nid2obj(NID_any_policy), 0)) == NULL)
         goto bad_tree;
-    if (level_add_node(level, data, NULL, tree) == NULL) {
+    if (level_add_node(level, data, NULL, tree, 1) == NULL) {
         policy_data_free(data);
         goto bad_tree;
     }
@@ -243,7 +258,8 @@ static int tree_init(X509_POLICY_TREE **ptree, STACK_OF(X509) *certs,
  * Return value: 1 on success, 0 otherwise
  */
 static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
-                                    X509_POLICY_DATA *data)
+                                    X509_POLICY_DATA *data,
+                                    X509_POLICY_TREE *tree)
 {
     X509_POLICY_LEVEL *last = curr - 1;
     int i, matched = 0;
@@ -253,13 +269,13 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
         X509_POLICY_NODE *node = sk_X509_POLICY_NODE_value(last->nodes, i);
 
         if (policy_node_match(last, node, data->valid_policy)) {
-            if (level_add_node(curr, data, node, NULL) == NULL)
+            if (level_add_node(curr, data, node, tree, 0) == NULL)
                 return 0;
             matched = 1;
         }
     }
     if (!matched && last->anyPolicy) {
-        if (level_add_node(curr, data, last->anyPolicy, NULL) == NULL)
+        if (level_add_node(curr, data, last->anyPolicy, tree, 0) == NULL)
             return 0;
     }
     return 1;
@@ -272,7 +288,8 @@ static int tree_link_matching_nodes(X509_POLICY_LEVEL *curr,
  * Return value: 1 on success, 0 otherwise.
  */
 static int tree_link_nodes(X509_POLICY_LEVEL *curr,
-                           const X509_POLICY_CACHE *cache)
+                           const X509_POLICY_CACHE *cache,
+                           X509_POLICY_TREE *tree)
 {
     int i;
 
@@ -280,7 +297,7 @@ static int tree_link_nodes(X509_POLICY_LEVEL *curr,
         X509_POLICY_DATA *data = sk_X509_POLICY_DATA_value(cache->data, i);
 
         /* Look for matching nodes in previous level */
-        if (!tree_link_matching_nodes(curr, data))
+        if (!tree_link_matching_nodes(curr, data, tree))
             return 0;
     }
     return 1;
@@ -311,7 +328,7 @@ static int tree_add_unmatched(X509_POLICY_LEVEL *curr,
     /* Curr may not have anyPolicy */
     data->qualifier_set = cache->anyPolicy->qualifier_set;
     data->flags |= POLICY_DATA_FLAG_SHARED_QUALIFIERS;
-    if (level_add_node(curr, data, node, tree) == NULL) {
+    if (level_add_node(curr, data, node, tree, 1) == NULL) {
         policy_data_free(data);
         return 0;
     }
@@ -373,7 +390,7 @@ static int tree_link_any(X509_POLICY_LEVEL *curr,
     }
     /* Finally add link to anyPolicy */
     if (last->anyPolicy &&
-        level_add_node(curr, cache->anyPolicy, last->anyPolicy, NULL) == NULL)
+        level_add_node(curr, cache->anyPolicy, last->anyPolicy, tree, 0) == NULL)
         return 0;
     return 1;
 }
@@ -555,7 +572,7 @@ static int tree_calculate_user_set(X509_POLICY_TREE *tree,
             extra->qualifier_set = anyPolicy->data->qualifier_set;
             extra->flags = POLICY_DATA_FLAG_SHARED_QUALIFIERS
                 | POLICY_DATA_FLAG_EXTRA_NODE;
-            node = level_add_node(NULL, extra, anyPolicy->parent, tree);
+            node = level_add_node(NULL, extra, anyPolicy->parent, tree, 1);
         }
         if (!tree->user_policies) {
             tree->user_policies = sk_X509_POLICY_NODE_new_null();
@@ -582,7 +599,7 @@ static int tree_evaluate(X509_POLICY_TREE *tree)
 
     for (i = 1; i < tree->nlevel; i++, curr++) {
         cache = policy_cache_set(curr->cert);
-        if (!tree_link_nodes(curr, cache))
+        if (!tree_link_nodes(curr, cache, tree))
             return X509_PCY_TREE_INTERNAL;
 
         if (!(curr->flags & X509_V_FLAG_INHIBIT_ANY)