diff --git a/maven-surefire-common/src/main/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfiguration.java b/maven-surefire-common/src/main/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfiguration.java
index 5e29d1ed31..a13de8fb86 100644
--- a/maven-surefire-common/src/main/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfiguration.java
+++ b/maven-surefire-common/src/main/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfiguration.java
@@ -179,6 +179,11 @@ static String relativize(@Nonnull Path parent, @Nonnull Path child) throws Illeg
     }
 
     static String toAbsoluteUri(@Nonnull Path absolutePath) {
+        // UNC paths need to be written as file:////
+        // see https://bugs.openjdk.org/browse/JDK-8320760
+        if (absolutePath.toString().startsWith("\\\\")) {
+            return absolutePath.toFile().toURI().toASCIIString();
+        }
         return absolutePath.toUri().toASCIIString();
     }
 
diff --git a/maven-surefire-common/src/test/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfigurationTest.java b/maven-surefire-common/src/test/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfigurationTest.java
index 23d850de89..9a9bf430ff 100644
--- a/maven-surefire-common/src/test/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfigurationTest.java
+++ b/maven-surefire-common/src/test/java/org/apache/maven/plugin/surefire/booterclient/JarManifestForkConfigurationTest.java
@@ -31,20 +31,24 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
 import org.mockito.invocation.InvocationOnMock;
 import org.mockito.stubbing.Answer;
 import org.powermock.core.classloader.annotations.PowerMockIgnore;
 import org.powermock.core.classloader.annotations.PrepareForTest;
 import org.powermock.modules.junit4.PowerMockRunner;
+import org.powermock.modules.junit4.PowerMockRunnerDelegate;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.apache.maven.plugin.surefire.booterclient.JarManifestForkConfiguration.escapeUri;
 import static org.apache.maven.plugin.surefire.booterclient.JarManifestForkConfiguration.relativize;
 import static org.apache.maven.plugin.surefire.booterclient.JarManifestForkConfiguration.toAbsoluteUri;
 import static org.apache.maven.plugin.surefire.booterclient.JarManifestForkConfiguration.toClasspathElementUri;
+import static org.apache.maven.surefire.shared.lang3.SystemUtils.IS_OS_WINDOWS;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.util.Files.delete;
 import static org.assertj.core.util.Files.newTemporaryFolder;
+import static org.junit.Assume.assumeTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyString;
@@ -57,6 +61,7 @@
  * Unit tests for {@link JarManifestForkConfiguration}.
  */
 @RunWith(PowerMockRunner.class)
+@PowerMockRunnerDelegate(JUnit4.class)
 @PrepareForTest({JarManifestForkConfiguration.class, InPluginProcessDumpSingleton.class})
 @PowerMockIgnore({"org.jacoco.agent.rt.*", "com.vladium.emma.rt.*"})
 public class JarManifestForkConfigurationTest {
@@ -163,6 +168,33 @@ public URI answer(InvocationOnMock invocation) throws URISyntaxException {
                 .isEqualTo("file:///X:/Users/me/.m2/repository/grp/art/1.0/art-1.0.jar");
     }
 
+    @Test
+    public void uncWindows() throws Exception {
+        assumeTrue(IS_OS_WINDOWS);
+        mockStatic(JarManifestForkConfiguration.class);
+        mockStatic(InPluginProcessDumpSingleton.class);
+        when(InPluginProcessDumpSingleton.getSingleton()).thenReturn(mock(InPluginProcessDumpSingleton.class));
+        Path parent = mock(Path.class);
+        when(parent.toString()).thenReturn("C:\\Windows\\Temp\\surefire");
+        Path classPathElement = mock(Path.class);
+        when(classPathElement.toString()).thenReturn("\\\\server\\grp\\art\\1.0\\art-1.0.jar");
+        when(classPathElement.toFile()).thenAnswer(new Answer<File>() {
+            @Override
+            public File answer(InvocationOnMock invocation) {
+                String path = invocation.getMock().toString();
+                return new File(path);
+            }
+        });
+        when(relativize(same(parent), same(classPathElement)))
+                .thenThrow(new IllegalArgumentException("'other' has different root"));
+        when(toClasspathElementUri(same(parent), same(classPathElement), same(dumpDirectory), anyBoolean()))
+                .thenCallRealMethod();
+        when(escapeUri(anyString(), any(Charset.class))).thenCallRealMethod();
+        when(toAbsoluteUri(same(classPathElement))).thenCallRealMethod();
+        assertThat(toClasspathElementUri(parent, classPathElement, dumpDirectory, true).uri)
+                .isEqualTo("file:////server/grp/art/1.0/art-1.0.jar");
+    }
+
     @Test
     @SuppressWarnings("checkstyle:magicnumber")
     public void shouldEscapeUri() throws Exception {