diff --git a/apps/emqx/src/emqx_schema.erl b/apps/emqx/src/emqx_schema.erl
index 4c26f86f9..1024cef48 100644
--- a/apps/emqx/src/emqx_schema.erl
+++ b/apps/emqx/src/emqx_schema.erl
@@ -399,7 +399,7 @@ fields("mqtt") ->
             sc(
                 range(1, 65535),
                 #{
-                    default => 65535,
+                    default => 128,
                     desc => ?DESC(mqtt_max_topic_levels)
                 }
             )},
diff --git a/changes/v5.0.11-en.md b/changes/v5.0.11-en.md
index abcf14bc4..def22e17c 100644
--- a/changes/v5.0.11-en.md
+++ b/changes/v5.0.11-en.md
@@ -19,6 +19,7 @@
 
 - Improve node name generation rules to avoid potential atom table overflow risk [#9387](https://github.com/emqx/emqx/pull/9387).
 
+- Set the default value for the maximum level of a topic to 128 [#9406](https://github.com/emqx/emqx/pull/9406).
 
 ## Bug fixes
 
diff --git a/changes/v5.0.11-zh.md b/changes/v5.0.11-zh.md
index 19ee5c125..7a4e770f9 100644
--- a/changes/v5.0.11-zh.md
+++ b/changes/v5.0.11-zh.md
@@ -17,6 +17,8 @@
 
 - 改进了节点名称生成规则，以避免潜在的原子表溢出风险 [#9387](https://github.com/emqx/emqx/pull/9387)。
 
+- 将主题的最大层级限制的默认值设置为128 [#9406](https://github.com/emqx/emqx/pull/9406)。
+
 ## 修复
 
 - 修复 helm chart 的 `ssl.existingName` 选项不起作用 [#9307](https://github.com/emqx/emqx/issues/9307)。