Merge branch '6.4.x' into 6.5.x

Closes gh-17580

Author: rwinch

config/src/main/java/org/springframework/security/config/annotation/AbstractConfiguredSecurityBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,6 +50,7 @@
  * @param <O> The object that this builder returns
  * @param <B> The type of this builder (that is returned by the base class)
  * @author Rob Winch
+ * @author DingHao
  * @see WebSecurity
  */
 public abstract class AbstractConfiguredSecurityBuilder<O, B extends SecurityBuilder<O>>
@@ -59,7 +60,7 @@ public abstract class AbstractConfiguredSecurityBuilder<O, B extends SecurityBui
 
 	private final LinkedHashMap<Class<? extends SecurityConfigurer<O, B>>, List<SecurityConfigurer<O, B>>> configurers = new LinkedHashMap<>();
 
-	private final List<SecurityConfigurer<O, B>> configurersAddedInInitializing = new ArrayList<>();
+	private List<SecurityConfigurer<O, B>> configurersAddedInInitializing = new ArrayList<>();
 
 	private final Map<Class<?>, Object> sharedObjects = new HashMap<>();
 
@@ -386,8 +387,12 @@ private void init() throws Exception {
 		for (SecurityConfigurer<O, B> configurer : configurers) {
 			configurer.init((B) this);
 		}
-		for (SecurityConfigurer<O, B> configurer : this.configurersAddedInInitializing) {
-			configurer.init((B) this);
+		while (!this.configurersAddedInInitializing.isEmpty()) {
+			List<SecurityConfigurer<O, B>> toInit = this.configurersAddedInInitializing;
+			this.configurersAddedInInitializing = new ArrayList<>();
+			for (SecurityConfigurer<O, B> configurer : toInit) {
+				configurer.init((B) this);
+			}
 		}
 	}
 

config/src/test/java/org/springframework/security/config/annotation/web/AbstractConfiguredSecurityBuilderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -163,6 +163,36 @@ public void withWhenDuplicateConfigurerAddedThenDuplicateConfigurerRemoved() thr
 		assertThat(this.builder.getConfigurers(TestSecurityConfigurer.class)).hasSize(1);
 	}
 
+	@Test
+	public void withWhenConfigurerAddInitializing() throws Exception {
+		this.builder.with(new AppliesNestedConfigurer(), Customizer.withDefaults());
+		assertThat(this.builder.build()).isEqualTo("success");
+	}
+
+	private static class AppliesNestedConfigurer
+			extends SecurityConfigurerAdapter<Object, TestConfiguredSecurityBuilder> {
+
+		@Override
+		public void init(TestConfiguredSecurityBuilder builder) throws Exception {
+			builder.with(new NestedConfigurer(), Customizer.withDefaults());
+		}
+
+	}
+
+	private static class NestedConfigurer extends SecurityConfigurerAdapter<Object, TestConfiguredSecurityBuilder> {
+
+		@Override
+		public void init(TestConfiguredSecurityBuilder http) throws Exception {
+			http.with(new DoubleNestedConfigurer(), Customizer.withDefaults());
+		}
+
+	}
+
+	private static class DoubleNestedConfigurer
+			extends SecurityConfigurerAdapter<Object, TestConfiguredSecurityBuilder> {
+
+	}
+
 	private static class ApplyAndRemoveSecurityConfigurer
 			extends SecurityConfigurerAdapter<Object, TestConfiguredSecurityBuilder> {