diff --git a/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpReceiverOverHTTP.java b/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpReceiverOverHTTP.java
index b6350461cd27..9dae09c1d51d 100644
--- a/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpReceiverOverHTTP.java
+++ b/jetty-client/src/main/java/org/eclipse/jetty/client/http/HttpReceiverOverHTTP.java
@@ -46,6 +46,7 @@ public class HttpReceiverOverHTTP extends HttpReceiver implements HttpParser.Res
     private RetainableByteBuffer networkBuffer;
     private boolean shutdown;
     private boolean complete;
+    private boolean unsolicited;
 
     public HttpReceiverOverHTTP(HttpChannelOverHTTP channel)
     {
@@ -264,6 +265,7 @@ public int getHeaderCacheSize()
     public boolean startResponse(HttpVersion version, int status, String reason)
     {
         HttpExchange exchange = getHttpExchange();
+        unsolicited = exchange == null;
         if (exchange == null)
             return false;
 
@@ -279,7 +281,8 @@ public boolean startResponse(HttpVersion version, int status, String reason)
     public void parsedHeader(HttpField field)
     {
         HttpExchange exchange = getHttpExchange();
-        if (exchange == null)
+        unsolicited |= exchange == null;
+        if (unsolicited)
             return;
 
         responseHeader(exchange, field);
@@ -289,7 +292,8 @@ public void parsedHeader(HttpField field)
     public boolean headerComplete()
     {
         HttpExchange exchange = getHttpExchange();
-        if (exchange == null)
+        unsolicited |= exchange == null;
+        if (unsolicited)
             return false;
 
         return !responseHeaders(exchange);
@@ -299,7 +303,8 @@ public boolean headerComplete()
     public boolean content(ByteBuffer buffer)
     {
         HttpExchange exchange = getHttpExchange();
-        if (exchange == null)
+        unsolicited |= exchange == null;
+        if (unsolicited)
             return false;
 
         RetainableByteBuffer networkBuffer = this.networkBuffer;
@@ -321,7 +326,8 @@ public boolean contentComplete()
     public void parsedTrailer(HttpField trailer)
     {
         HttpExchange exchange = getHttpExchange();
-        if (exchange == null)
+        unsolicited |= exchange == null;
+        if (unsolicited)
             return;
 
         exchange.getResponse().trailer(trailer);
@@ -331,8 +337,12 @@ public void parsedTrailer(HttpField trailer)
     public boolean messageComplete()
     {
         HttpExchange exchange = getHttpExchange();
-        if (exchange == null)
+        if (exchange == null || unsolicited)
+        {
+            // We received an unsolicited response from the server.
+            getHttpConnection().close();
             return false;
+        }
 
         int status = exchange.getResponse().getStatus();
         if (status != HttpStatus.CONTINUE_100)
@@ -349,7 +359,7 @@ public void earlyEOF()
     {
         HttpExchange exchange = getHttpExchange();
         HttpConnectionOverHTTP connection = getHttpConnection();
-        if (exchange == null)
+        if (exchange == null || unsolicited)
             connection.close();
         else
             failAndClose(new EOFException(String.valueOf(connection)));
@@ -359,7 +369,11 @@ public void earlyEOF()
     public void badMessage(BadMessageException failure)
     {
         HttpExchange exchange = getHttpExchange();
-        if (exchange != null)
+        if (exchange == null || unsolicited)
+        {
+            getHttpConnection().close();
+        }
+        else
         {
             HttpResponse response = exchange.getResponse();
             response.status(failure.getCode()).reason(failure.getReason());
diff --git a/jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientTest.java b/jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientTest.java
index 21603d3c8163..00245183ed3b 100644
--- a/jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientTest.java
+++ b/jetty-client/src/test/java/org/eclipse/jetty/client/HttpClientTest.java
@@ -1839,6 +1839,61 @@ public void onComplete(Result result)
         assertArrayEquals(bytes, baos.toByteArray());
     }
 
+    @ParameterizedTest
+    @ArgumentsSource(ScenarioProvider.class)
+    public void testUnsolicitedResponseBytesFromServer(Scenario scenario) throws Exception
+    {
+        String response = "" +
+            "HTTP/1.1 408 Request Timeout\r\n" +
+            "Content-Length: 0\r\n" +
+            "Connection: close\r\n" +
+            "\r\n";
+        testUnsolicitedBytesFromServer(scenario, response);
+    }
+
+    @ParameterizedTest
+    @ArgumentsSource(ScenarioProvider.class)
+    public void testUnsolicitedInvalidBytesFromServer(Scenario scenario) throws Exception
+    {
+        String response = "ABCDEF";
+        testUnsolicitedBytesFromServer(scenario, response);
+    }
+
+    private void testUnsolicitedBytesFromServer(Scenario scenario, String bytesFromServer) throws Exception
+    {
+        try (ServerSocket server = new ServerSocket(0))
+        {
+            HttpClientTransport transport = new HttpClientTransportOverHTTP(1);
+            transport.setConnectionPoolFactory(destination ->
+            {
+                ConnectionPool connectionPool = new DuplexConnectionPool(destination, 1, destination);
+                connectionPool.preCreateConnections(1);
+                return connectionPool;
+            });
+            startClient(scenario, transport, null);
+
+            String host = "localhost";
+            int port = server.getLocalPort();
+
+            // Resolve the destination which will pre-create a connection.
+            HttpDestination destination = client.resolveDestination(new Origin("http", host, port));
+
+            // Accept the connection and send an unsolicited 408.
+            try (Socket socket = server.accept())
+            {
+                OutputStream output = socket.getOutputStream();
+                output.write(bytesFromServer.getBytes(StandardCharsets.UTF_8));
+                output.flush();
+            }
+
+            // Give some time to the client to process the response.
+            Thread.sleep(1000);
+
+            AbstractConnectionPool pool = (AbstractConnectionPool)destination.getConnectionPool();
+            assertEquals(0, pool.getConnectionCount());
+        }
+    }
+
     private void assertCopyRequest(Request original)
     {
         Request copy = client.copyRequest((HttpRequest)original, original.getURI());