diff --git a/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java b/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java
index ac8f194376..8e9961208c 100644
--- a/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java
+++ b/spring-test/src/main/java/org/springframework/mock/web/MockHttpServletRequest.java
@@ -668,11 +668,14 @@ public class MockHttpServletRequest implements HttpServletRequest {
 
 	@Override
 	public String getServerName() {
-		String host = getHeader(HttpHeaders.HOST);
+		String rawHostHeader = getHeader(HttpHeaders.HOST);
+		String host = rawHostHeader;
 		if (host != null) {
 			host = host.trim();
 			if (host.startsWith("[")) {
-				host = host.substring(1, host.indexOf(']'));
+				int indexOfClosingBracket = host.indexOf(']');
+				Assert.state(indexOfClosingBracket > -1, () -> "Invalid Host header: " + rawHostHeader);
+				host = host.substring(0, indexOfClosingBracket + 1);
 			}
 			else if (host.contains(":")) {
 				host = host.substring(0, host.indexOf(':'));
@@ -690,12 +693,15 @@ public class MockHttpServletRequest implements HttpServletRequest {
 
 	@Override
 	public int getServerPort() {
-		String host = getHeader(HttpHeaders.HOST);
+		String rawHostHeader = getHeader(HttpHeaders.HOST);
+		String host = rawHostHeader;
 		if (host != null) {
 			host = host.trim();
 			int idx;
 			if (host.startsWith("[")) {
-				idx = host.indexOf(':', host.indexOf(']'));
+				int indexOfClosingBracket = host.indexOf(']');
+				Assert.state(indexOfClosingBracket > -1, () -> "Invalid Host header: " + rawHostHeader);
+				idx = host.indexOf(':', indexOfClosingBracket);
 			}
 			else {
 				idx = host.indexOf(':');
diff --git a/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java b/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java
index 9f58f85922..76104fbb6f 100644
--- a/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java
+++ b/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -17,6 +17,7 @@
 package org.springframework.mock.web;
 
 import java.io.IOException;
+import java.net.URL;
 import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -37,6 +38,7 @@ import org.springframework.util.FileCopyUtils;
 import org.springframework.util.StreamUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
@@ -389,18 +391,25 @@ class MockHttpServletRequestTests {
 		assertThat(request.getServerName()).isEqualTo(testServer);
 	}
 
+	@Test
+	void getServerNameWithInvalidIpv6AddressViaHostHeader() {
+		request.addHeader(HOST, "[::ffff:abcd:abcd"); // missing closing bracket
+		assertThatIllegalStateException()
+			.isThrownBy(() -> request.getServerName())
+			.withMessageStartingWith("Invalid Host header: ");
+	}
+
 	@Test
 	void getServerNameViaHostHeaderAsIpv6AddressWithoutPort() {
-		String ipv6Address = "[2001:db8:0:1]";
-		request.addHeader(HOST, ipv6Address);
-		assertThat(request.getServerName()).isEqualTo("2001:db8:0:1");
+		String host = "[2001:db8:0:1]";
+		request.addHeader(HOST, host);
+		assertThat(request.getServerName()).isEqualTo(host);
 	}
 
 	@Test
 	void getServerNameViaHostHeaderAsIpv6AddressWithPort() {
-		String ipv6Address = "[2001:db8:0:1]:8081";
-		request.addHeader(HOST, ipv6Address);
-		assertThat(request.getServerName()).isEqualTo("2001:db8:0:1");
+		request.addHeader(HOST, "[2001:db8:0:1]:8081");
+		assertThat(request.getServerName()).isEqualTo("[2001:db8:0:1]");
 	}
 
 	@Test
@@ -414,6 +423,22 @@ class MockHttpServletRequestTests {
 		assertThat(request.getServerPort()).isEqualTo(8080);
 	}
 
+	@Test
+	void getServerPortWithInvalidIpv6AddressViaHostHeader() {
+		request.addHeader(HOST, "[::ffff:abcd:abcd:8080"); // missing closing bracket
+		assertThatIllegalStateException()
+			.isThrownBy(() -> request.getServerPort())
+			.withMessageStartingWith("Invalid Host header: ");
+	}
+
+	@Test
+	void getServerPortWithIpv6AddressAndInvalidPortViaHostHeader() {
+		request.addHeader(HOST, "[::ffff:abcd:abcd]:bogus"); // "bogus" is not a port number
+		assertThatExceptionOfType(NumberFormatException.class)
+			.isThrownBy(() -> request.getServerPort())
+			.withMessageContaining("bogus");
+	}
+
 	@Test
 	void getServerPortViaHostHeaderAsIpv6AddressWithoutPort() {
 		String testServer = "[2001:db8:0:1]";
@@ -478,6 +503,43 @@ class MockHttpServletRequestTests {
 		assertThat(requestURL.toString()).isEqualTo(("http://" + testServer));
 	}
 
+	@Test
+	void getRequestURLWithIpv6AddressViaServerNameWithoutPort() throws Exception {
+		request.setServerName("[::ffff:abcd:abcd]");
+		URL url = new java.net.URL(request.getRequestURL().toString());
+		assertThat(url).asString().isEqualTo("http://[::ffff:abcd:abcd]");
+	}
+
+	@Test
+	void getRequestURLWithIpv6AddressViaServerNameWithPort() throws Exception {
+		request.setServerName("[::ffff:abcd:abcd]");
+		request.setServerPort(9999);
+		URL url = new java.net.URL(request.getRequestURL().toString());
+		assertThat(url).asString().isEqualTo("http://[::ffff:abcd:abcd]:9999");
+	}
+
+	@Test
+	void getRequestURLWithInvalidIpv6AddressViaHostHeader() {
+		request.addHeader(HOST, "[::ffff:abcd:abcd"); // missing closing bracket
+		assertThatIllegalStateException()
+			.isThrownBy(() -> request.getRequestURL())
+			.withMessageStartingWith("Invalid Host header: ");
+	}
+
+	@Test
+	void getRequestURLWithIpv6AddressViaHostHeaderWithoutPort() throws Exception {
+		request.addHeader(HOST, "[::ffff:abcd:abcd]");
+		URL url = new java.net.URL(request.getRequestURL().toString());
+		assertThat(url).asString().isEqualTo("http://[::ffff:abcd:abcd]");
+	}
+
+	@Test
+	void getRequestURLWithIpv6AddressViaHostHeaderWithPort() throws Exception {
+		request.addHeader(HOST, "[::ffff:abcd:abcd]:9999");
+		URL url = new java.net.URL(request.getRequestURL().toString());
+		assertThat(url).asString().isEqualTo("http://[::ffff:abcd:abcd]:9999");
+	}
+
 	@Test
 	void getRequestURLWithNullRequestUri() {
 		request.setRequestURI(null);