diff --git a/plugins/core.c b/plugins/core.c
index 12c67b4b4e..2897453cac 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -214,30 +214,49 @@ CPUPluginState *qemu_plugin_create_vcpu_state(void)
 
 static void plugin_grow_scoreboards__locked(CPUState *cpu)
 {
-    if (cpu->cpu_index < plugin.scoreboard_alloc_size) {
+    size_t scoreboard_size = plugin.scoreboard_alloc_size;
+    bool need_realloc = false;
+
+    if (cpu->cpu_index < scoreboard_size) {
         return;
     }
 
-    bool need_realloc = FALSE;
-    while (cpu->cpu_index >= plugin.scoreboard_alloc_size) {
-        plugin.scoreboard_alloc_size *= 2;
-        need_realloc = TRUE;
+    while (cpu->cpu_index >= scoreboard_size) {
+        scoreboard_size *= 2;
+        need_realloc = true;
     }
 
-
-    if (!need_realloc || QLIST_EMPTY(&plugin.scoreboards)) {
-        /* nothing to do, we just updated sizes for future scoreboards */
+    if (!need_realloc) {
         return;
     }
 
+    if (QLIST_EMPTY(&plugin.scoreboards)) {
+        /* just update size for future scoreboards */
+        plugin.scoreboard_alloc_size = scoreboard_size;
+        return;
+    }
+
+    /*
+     * A scoreboard creation/deletion might be in progress. If a new vcpu is
+     * initialized at the same time, we are safe, as the new
+     * plugin.scoreboard_alloc_size was not yet written.
+     */
+    qemu_rec_mutex_unlock(&plugin.lock);
+
     /* cpus must be stopped, as tb might still use an existing scoreboard. */
     start_exclusive();
-    struct qemu_plugin_scoreboard *score;
-    QLIST_FOREACH(score, &plugin.scoreboards, entry) {
-        g_array_set_size(score->data, plugin.scoreboard_alloc_size);
+    /* re-acquire lock */
+    qemu_rec_mutex_lock(&plugin.lock);
+    /* in case another vcpu is created between unlock and exclusive section. */
+    if (scoreboard_size > plugin.scoreboard_alloc_size) {
+        struct qemu_plugin_scoreboard *score;
+        QLIST_FOREACH(score, &plugin.scoreboards, entry) {
+            g_array_set_size(score->data, scoreboard_size);
+        }
+        plugin.scoreboard_alloc_size = scoreboard_size;
+        /* force all tb to be flushed, as scoreboard pointers were changed. */
+        tb_flush(cpu);
     }
-    /* force all tb to be flushed, as scoreboard pointers were changed. */
-    tb_flush(cpu);
     end_exclusive();
 }