diff --git a/its/core-it-suite/src/test/java/org/apache/maven/it/IntegrationTestSuite.java b/its/core-it-suite/src/test/java/org/apache/maven/it/IntegrationTestSuite.java
index 73672ac392..43abb6a11e 100644
--- a/its/core-it-suite/src/test/java/org/apache/maven/it/IntegrationTestSuite.java
+++ b/its/core-it-suite/src/test/java/org/apache/maven/it/IntegrationTestSuite.java
@@ -86,6 +86,7 @@ public class IntegrationTestSuite
         // suite.addTestSuite( MavenIT0109ReleaseUpdateTest.class );
         // suite.addTestSuite( MavenIT0108SnapshotUpdateTest.class ); -- MNG-3137
 
+        suite.addTestSuite( MavenITmng4273RestrictedCoreRealmAccessForPluginTest.class );
         suite.addTestSuite( MavenITmng4270ArtifactHandlersFromPluginDepsTest.class );
         suite.addTestSuite( MavenITmng4269BadReactorResolutionFromOutDirTest.class );
         suite.addTestSuite( MavenITmng4262MakeLikeReactorDottedPathTest.class );
diff --git a/its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng4273RestrictedCoreRealmAccessForPluginTest.java b/its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng4273RestrictedCoreRealmAccessForPluginTest.java
new file mode 100644
index 0000000000..0a7145fcf2
--- /dev/null
+++ b/its/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng4273RestrictedCoreRealmAccessForPluginTest.java
@@ -0,0 +1,64 @@
+package org.apache.maven.it;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import org.apache.maven.it.Verifier;
+import org.apache.maven.it.util.ResourceExtractor;
+
+import java.io.File;
+import java.util.Properties;
+
+/**
+ * This is a test set for <a href="http://jira.codehaus.org/browse/MNG-4273">MNG-4273</a>.
+ *
+ * @author Benjamin Bentmann
+ */
+public class MavenITmng4273RestrictedCoreRealmAccessForPluginTest
+    extends AbstractMavenIntegrationTestCase
+{
+
+    public MavenITmng4273RestrictedCoreRealmAccessForPluginTest()
+    {
+        super( "[2.0.6,)" );
+    }
+
+    /**
+     * Verify that internal utility/implementation classes used by the Maven core do not leak into the plugin realm.
+     * Otherwise, we risk linkage errors when a plugin creates a custom class loader with parent-first delegation on
+     * top of the plugin realm because the custom class loader will prefer potentially incompatible classes from the
+     * core realm over classes from itself.
+     */
+    public void testit()
+        throws Exception
+    {
+        File testDir = ResourceExtractor.simpleExtractResources( getClass(), "/mng-4273" );
+
+        Verifier verifier = new Verifier( testDir.getAbsolutePath() );
+        verifier.setAutoclean( false );
+        verifier.executeGoal( "validate" );
+        verifier.verifyErrorFreeLog();
+        verifier.resetStreams();
+
+        Properties props = verifier.loadProperties( "target/class.properties" );
+        assertNull( props.getProperty( "org.codehaus.plexus.util.FileUtils$FilterWrapper" ) );
+        assertNull( props.getProperty( "org.apache.xerces.util.ParserConfigurationSettings" ) );
+    }
+
+}
diff --git a/its/core-it-suite/src/test/resources/mng-4273/pom.xml b/its/core-it-suite/src/test/resources/mng-4273/pom.xml
new file mode 100644
index 0000000000..4851c6d45a
--- /dev/null
+++ b/its/core-it-suite/src/test/resources/mng-4273/pom.xml
@@ -0,0 +1,69 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<!--
+Licensed to the Apache Software Foundation (ASF) under one
+or more contributor license agreements.  See the NOTICE file
+distributed with this work for additional information
+regarding copyright ownership.  The ASF licenses this file
+to you under the Apache License, Version 2.0 (the
+"License"); you may not use this file except in compliance
+with the License.  You may obtain a copy of the License at
+
+  http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+KIND, either express or implied.  See the License for the
+specific language governing permissions and limitations
+under the License.
+-->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>org.apache.maven.its.mng4273</groupId>
+  <artifactId>test</artifactId>
+  <version>0.1</version>
+  <packaging>maven-plugin</packaging>
+
+  <name>Maven Integration Test :: MNG-4273</name>
+  <description>
+    Verify that internal utility/implementation classes used by the Maven core do not leak into the plugin realm.
+    Otherwise, we risk linkage errors when a plugin creates a custom class loader with parent-first delegation on
+    top of the plugin realm because the custom class loader will prefer potentially incompatible classes from the
+    core realm over classes from itself.
+  </description>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.its.plugins</groupId>
+        <artifactId>maven-it-plugin-class-loader</artifactId>
+        <version>2.1-SNAPSHOT</version>
+        <configuration>
+          <projectClassLoaderOutput>target/class.properties</projectClassLoaderOutput>
+          <!--
+          To exhibit the bug, the following classes have been chosen:
+          - org.codehaus.plexus.util.FileUtils$FilterWrapper
+            This is only available in plexus-utils:1.2+ and hence present in all recent Maven versions that try to hide plexus-utils.
+            We can't use a simpler class like StringUtils because there's a hack in Maven 2.x that automatically puts
+            plexus-utils:1.1 in the plugin realm.
+          - org.apache.xerces.util.ParserConfigurationSettings
+            This is from xercesMinimal:1.9.6.2 or xercesImpl:2.6.2 and the crux from the original issue report.
+          -->
+          <classNames>org.codehaus.plexus.util.FileUtils$FilterWrapper,org.apache.xerces.util.ParserConfigurationSettings</classNames>
+        </configuration>
+        <executions>
+          <execution>
+            <id>test</id>
+            <phase>validate</phase>
+            <goals>
+              <goal>load-dependencies</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>