diff --git a/web/pgadmin/feature_tests/xss_checks_panels_and_query_tool_test.py b/web/pgadmin/feature_tests/xss_checks_panels_and_query_tool_test.py
new file mode 100644
index 000000000..526d4e766
--- /dev/null
+++ b/web/pgadmin/feature_tests/xss_checks_panels_and_query_tool_test.py
@@ -0,0 +1,189 @@
+##########################################################################
+#
+# pgAdmin 4 - PostgreSQL Tools
+#
+# Copyright (C) 2013 - 2017, The pgAdmin Development Team
+# This software is released under the PostgreSQL Licence
+#
+##########################################################################
+
+from selenium.webdriver import ActionChains
+from regression.python_test_utils import test_utils
+from regression.feature_utils.base_feature_test import BaseFeatureTest
+import time
+
+class CheckForXssFeatureTest(BaseFeatureTest):
+    """
+    Tests to check if pgAdmin4 is vulnerable to XSS.
+
+    Here we will check html source code for escaped characters if we
+    found them in the code then we are not vulnerable otherwise we might.
+
+    We will cover,
+        1) Browser Tree (aciTree)
+        2) Properties Tab (BackFrom)
+        3) Dependents Tab (BackGrid)
+        4) SQL Tab (Code Mirror)
+        5) Query Tool (SlickGrid)
+    """
+
+    scenarios = [
+        ("Test XSS check for panels and query tool", dict())
+    ]
+
+    def before(self):
+        connection = test_utils.get_db_connection(self.server['db'],
+                                                  self.server['username'],
+                                                  self.server['db_password'],
+                                                  self.server['host'],
+                                                  self.server['port'])
+        test_utils.drop_database(connection, "acceptance_test_db")
+        test_utils.create_database(self.server, "acceptance_test_db")
+        test_utils.create_table(self.server, "acceptance_test_db",
+                                "<h1>X")
+
+        # This is needed to test dependents tab (eg: BackGrid)
+        test_utils.create_constraint(self.server, "acceptance_test_db",
+                                     "<h1>X",
+                                     "unique", "<h1 onmouseover='console.log(2);'>Y")
+
+    def runTest(self):
+        self.page.wait_for_spinner_to_disappear()
+        self._connects_to_server()
+        self._tables_node_expandable()
+        self._check_xss_in_browser_tree()
+        self._check_xss_in_properties_tab()
+        self._check_xss_in_sql_tab()
+        self._check_xss_in_dependents_tab()
+
+        # Query tool
+        self._check_xss_in_query_tool()
+        self._close_query_tool()
+
+    def after(self):
+        time.sleep(1)
+        self.page.remove_server(self.server)
+        connection = test_utils.get_db_connection(self.server['db'],
+                                                  self.server['username'],
+                                                  self.server['db_password'],
+                                                  self.server['host'],
+                                                  self.server['port'])
+        test_utils.drop_database(connection, "acceptance_test_db")
+
+    def _connects_to_server(self):
+        self.page.find_by_xpath("//*[@class='aciTreeText' and .='Servers']").click()
+        self.page.driver.find_element_by_link_text("Object").click()
+        ActionChains(self.page.driver) \
+            .move_to_element(self.page.driver.find_element_by_link_text("Create")) \
+            .perform()
+        self.page.find_by_partial_link_text("Server...").click()
+
+        server_config = self.server
+        self.page.fill_input_by_field_name("name", server_config['name'])
+        self.page.find_by_partial_link_text("Connection").click()
+        self.page.fill_input_by_field_name("host", server_config['host'])
+        self.page.fill_input_by_field_name("port", server_config['port'])
+        self.page.fill_input_by_field_name("username", server_config['username'])
+        self.page.fill_input_by_field_name("password", server_config['db_password'])
+        self.page.find_by_xpath("//button[contains(.,'Save')]").click()
+
+    def _tables_node_expandable(self):
+        self.page.toggle_open_tree_item(self.server['name'])
+        self.page.toggle_open_tree_item('Databases')
+        self.page.toggle_open_tree_item('acceptance_test_db')
+        self.page.toggle_open_tree_item('Schemas')
+        self.page.toggle_open_tree_item('public')
+        self.page.toggle_open_tree_item('Tables')
+        self.page.select_tree_item("<h1>X")
+
+    def _check_xss_in_browser_tree(self):
+        # Fetch the inner html & check for escaped characters
+        source_code = self.page.find_by_xpath(
+            "//*[@id='tree']"
+        ).get_attribute('innerHTML')
+
+        self._check_escaped_characters(
+            source_code,
+            "&lt;h1&gt;X",
+            "Browser tree"
+        )
+
+    def _check_xss_in_properties_tab(self):
+        self.page.click_tab("Properties")
+        source_code = self.page.find_by_xpath(
+            "//span[contains(@class,'uneditable-input')]"
+        ).get_attribute('innerHTML')
+        self._check_escaped_characters(
+            source_code,
+            "&lt;h1&gt;X",
+            "Properties tab (Backform Control)"
+        )
+
+
+    def _check_xss_in_sql_tab(self):
+        self.page.click_tab("SQL")
+        # Fetch the inner html & check for escaped characters
+        source_code = self.page.find_by_xpath(
+            "//*[contains(@class,'CodeMirror-lines') and contains(.,'CREATE TABLE')]"
+        ).get_attribute('innerHTML')
+
+        self._check_escaped_characters(
+            source_code,
+            "&lt;h1&gt;X",
+            "SQL tab (Code Mirror)"
+        )
+
+    def _check_xss_in_dependents_tab(self): # Create any constraint with xss name to test this
+        self.page.click_tab("Dependents")
+
+        source_code = self.page.find_by_xpath(
+            "//*[@id='5']/table/tbody/tr/td/div/div/div[2]/table/tbody/tr/td[2]"
+        ).get_attribute('innerHTML')
+
+        self._check_escaped_characters(
+            source_code,
+            "public.&lt;h1 onmouseover='console.log(2);'&gt;Y",
+            "Dependents tab (BackGrid)"
+        )
+
+    def _check_xss_in_query_tool(self):
+        self.page.driver.find_element_by_link_text("Tools").click()
+        self.page.find_by_partial_link_text("Query Tool").click()
+        time.sleep(3)
+        self.page.driver.switch_to.frame(self.page.driver.find_element_by_tag_name('iframe'))
+        self.page.fill_codemirror_area_with("select '<img src=\"x\" onerror=\"console.log(1)\">'")
+        time.sleep(1)
+        self.page.find_by_id("btn-flash").click()
+        time.sleep(2)
+
+        source_code = self.page.find_by_xpath(
+            "//*[@id='0']//*[@id='datagrid']/div[5]/div/div[1]/div[2]"
+        ).get_attribute('innerHTML')
+
+        self._check_escaped_characters(
+            source_code,
+            '&lt;img src="x" onerror="console.log(1)"&gt;',
+            "Query tool (SlickGrid)"
+        )
+
+    def _close_query_tool(self):
+        self.page.driver.switch_to_default_content()
+        self.page.click_element(
+            self.page.find_by_xpath("//*[@id='dockerContainer']/div/div[3]/div/div[2]/div[1]")
+        )
+        time.sleep(0.5)
+        self.page.driver.switch_to.frame(self.page.driver.find_element_by_tag_name('iframe'))
+        time.sleep(1)
+        self.page.click_element(self.page.find_by_xpath("//button[contains(.,'Yes')]"))
+        time.sleep(0.5)
+        self.page.driver.switch_to_default_content()
+
+
+    def _check_escaped_characters(self, source_code, string_to_find, source):
+        # For XSS we need to search against element's html code
+        if source_code.find(string_to_find) == -1:
+            # No escaped characters found
+            assert False, "{0} might be vulnerable to XSS ".format(source)
+        else:
+            # escaped characters found
+            assert True
diff --git a/web/pgadmin/feature_tests/xss_checks_pgadmin_debugger_test.py b/web/pgadmin/feature_tests/xss_checks_pgadmin_debugger_test.py
new file mode 100644
index 000000000..8b018fedc
--- /dev/null
+++ b/web/pgadmin/feature_tests/xss_checks_pgadmin_debugger_test.py
@@ -0,0 +1,119 @@
+##########################################################################
+#
+# pgAdmin 4 - PostgreSQL Tools
+#
+# Copyright (C) 2013 - 2017, The pgAdmin Development Team
+# This software is released under the PostgreSQL Licence
+#
+##########################################################################
+
+from selenium.webdriver import ActionChains
+from regression.python_test_utils import test_utils
+from regression.feature_utils.base_feature_test import BaseFeatureTest
+import time
+
+class CheckDebuggerForXssFeatureTest(BaseFeatureTest):
+    """Tests to check if Debugger is vulnerable to XSS."""
+
+    scenarios = [
+        ("Test table DDL generation", dict())
+    ]
+
+    def before(self):
+        # Some test function is needed for debugger
+        test_utils.create_debug_function(self.server, "postgres",
+                                   "test_function")
+
+    def runTest(self):
+        self.page.wait_for_spinner_to_disappear()
+        self._connects_to_server()
+        self._function_node_expandable()
+        self._debug_function()
+
+    def after(self):
+        time.sleep(0.5)
+        test_utils.drop_debug_function(self.server, "postgres",
+                                   "test_function")
+        self.page.remove_server(self.server)
+
+    def _connects_to_server(self):
+        self.page.find_by_xpath("//*[@class='aciTreeText' and .='Servers']").click()
+        self.page.driver.find_element_by_link_text("Object").click()
+        ActionChains(self.page.driver) \
+            .move_to_element(self.page.driver.find_element_by_link_text("Create")) \
+            .perform()
+        self.page.find_by_partial_link_text("Server...").click()
+
+        server_config = self.server
+        self.page.fill_input_by_field_name("name", server_config['name'])
+        self.page.find_by_partial_link_text("Connection").click()
+        self.page.fill_input_by_field_name("host", server_config['host'])
+        self.page.fill_input_by_field_name("port", server_config['port'])
+        self.page.fill_input_by_field_name("username", server_config['username'])
+        self.page.fill_input_by_field_name("password", server_config['db_password'])
+        self.page.find_by_xpath("//button[contains(.,'Save')]").click()
+
+    def _function_node_expandable(self):
+        self.page.toggle_open_tree_item(self.server['name'])
+        self.page.toggle_open_tree_item('Databases')
+        self.page.toggle_open_tree_item('postgres')
+        self.page.toggle_open_tree_item('Schemas')
+        self.page.toggle_open_tree_item('public')
+        self.page.toggle_open_tree_item('Functions')
+        self.page.select_tree_item("test_function()")
+
+    def _debug_function(self):
+        self.page.driver.find_element_by_link_text("Object").click()
+        ActionChains(self.page.driver) \
+            .move_to_element(self.page.driver.find_element_by_link_text("Debugging")) \
+            .perform()
+        self.page.driver.find_element_by_link_text("Debug").click()
+        time.sleep(0.5)
+        # We need to check if debugger plugin is installed or not
+        try:
+            is_error = self.page.find_by_xpath(
+                "//div[contains(@class,'ajs-header')]"
+            ).text
+        except Exception as e:
+            is_error = None
+
+        # If debugger plugin is not found
+        if is_error and is_error == "Debugger Error":
+            self.page.click_modal_ok()
+            self.skipTest("Please make sure that debugger plugin is properly configured")
+        else:
+            time.sleep(2)
+            self.page.driver.switch_to.frame(self.page.driver.find_element_by_tag_name('iframe'))
+            self.page.click_element(self.page.driver.find_elements_by_xpath("//button")[2])
+            time.sleep(2)
+
+            # Only this tab is vulnerable rest are BackGrid & Code Mirror control
+            # which are already tested in Query tool test case
+            self.page.click_tab("Messages")
+            source_code = self.page.find_by_xpath(
+                "//*[@id='messages']"
+            ).get_attribute('innerHTML')
+
+            self._check_escaped_characters(
+                source_code,
+                'NOTICE:  &lt;img src="x" onerror="console.log(1)"&gt;',
+                'Debugger'
+            )
+            self._close_debugger()
+
+    def _close_debugger(self):
+        time.sleep(0.5)
+        self.page.driver.switch_to_default_content()
+        time.sleep(0.5)
+        self.page.click_element(
+            self.page.find_by_xpath("//*[@id='dockerContainer']/div/div[3]/div/div[2]/div[1]")
+        )
+
+    def _check_escaped_characters(self, source_code, string_to_find, source):
+        # For XSS we need to search against element's html code
+        if source_code.find(string_to_find) == -1:
+            # No escaped characters found
+            assert False, "{0} might be vulnerable to XSS ".format(source)
+        else:
+            # escaped characters found
+            assert True
diff --git a/web/pgadmin/static/js/slickgrid/slick.pgadmin.formatters.js b/web/pgadmin/static/js/slickgrid/slick.pgadmin.formatters.js
index b066095e1..290bdddac 100644
--- a/web/pgadmin/static/js/slickgrid/slick.pgadmin.formatters.js
+++ b/web/pgadmin/static/js/slickgrid/slick.pgadmin.formatters.js
@@ -24,7 +24,7 @@
     } else {
       // Stringify only if it's json object
       if (typeof value === "object" && !Array.isArray(value)) {
-        return JSON.stringify(value);
+        return _.escape(JSON.stringify(value));
       } else if (Array.isArray(value)) {
         var temp = [];
         $.each(value, function(i, val) {
@@ -34,9 +34,9 @@
             temp.push(val)
           }
         });
-        return "[" + temp.join() + "]"
+        return _.escape("[" + temp.join() + "]")
       } else {
-        return value;
+        return _.escape(value);
       }
     }
   }
@@ -49,7 +49,7 @@
       return '';
     }
     else {
-      return "<span style='float:right'>" + value + "</span>";
+      return "<span style='float:right'>" + _.escape(value) + "</span>";
     }
   }
 
@@ -70,7 +70,7 @@
       return "<span class='pull-left'>[null]</span>";
     }
     else {
-      return value;
+      return _.escape(value);
     }
   }
 
diff --git a/web/pgadmin/tools/debugger/__init__.py b/web/pgadmin/tools/debugger/__init__.py
index 03ba9b12e..9c435ff5a 100644
--- a/web/pgadmin/tools/debugger/__init__.py
+++ b/web/pgadmin/tools/debugger/__init__.py
@@ -1425,10 +1425,10 @@ def poll_end_execution_result(trans_id):
             status = 'Success'
             additional_msgs = conn.messages()
             if len(additional_msgs) > 0:
-                additional_msgs = [msg.strip("<br>") for msg in additional_msgs]
-                additional_msgs = "<br>".join(additional_msgs)
+                additional_msgs = [msg.strip("\n") for msg in additional_msgs]
+                additional_msgs = "\n".join(additional_msgs)
                 if statusmsg:
-                    statusmsg = additional_msgs + "<br>" + statusmsg
+                    statusmsg = additional_msgs + "\n" + statusmsg
                 else:
                     statusmsg = additional_msgs
 
@@ -1443,10 +1443,10 @@ def poll_end_execution_result(trans_id):
                 status = 'Success'
                 additional_msgs = conn.messages()
                 if len(additional_msgs) > 0:
-                    additional_msgs = [msg.strip("<br>") for msg in additional_msgs]
-                    additional_msgs = "<br>".join(additional_msgs)
+                    additional_msgs = [msg.strip("\n") for msg in additional_msgs]
+                    additional_msgs = "\n".join(additional_msgs)
                     if statusmsg:
-                        statusmsg = additional_msgs + "<br>" + statusmsg
+                        statusmsg = additional_msgs + "\n" + statusmsg
                     else:
                         statusmsg = additional_msgs
 
@@ -1460,9 +1460,9 @@ def poll_end_execution_result(trans_id):
             additional_msgs = conn.messages()
             if len(additional_msgs) > 0:
                 additional_msgs = [msg.strip("\n") for msg in additional_msgs]
-                additional_msgs = "<br>".join(additional_msgs)
+                additional_msgs = "\n".join(additional_msgs)
                 if statusmsg:
-                    statusmsg = additional_msgs + "<br>" + statusmsg
+                    statusmsg = additional_msgs + "\n" + statusmsg
                 else:
                     statusmsg = additional_msgs
             return make_json_response(data={
diff --git a/web/pgadmin/tools/debugger/templates/debugger/js/direct.js b/web/pgadmin/tools/debugger/templates/debugger/js/direct.js
index 971b1135d..8bdfdda65 100644
--- a/web/pgadmin/tools/debugger/templates/debugger/js/direct.js
+++ b/web/pgadmin/tools/debugger/templates/debugger/js/direct.js
@@ -383,6 +383,9 @@ define(
 
     // This function will update messages tab
     update_messages: function(msg) {
+      // To prevent xss
+      msg = _.escape(msg);
+
       var old_msgs='', new_msgs='';
         old_msgs = pgTools.DirectDebug.messages_panel.$container.find('.messages').html();
         if(old_msgs) {
diff --git a/web/regression/feature_utils/pgadmin_page.py b/web/regression/feature_utils/pgadmin_page.py
index aa31bc047..3ebd8bcde 100644
--- a/web/regression/feature_utils/pgadmin_page.py
+++ b/web/regression/feature_utils/pgadmin_page.py
@@ -35,7 +35,10 @@ class PgadminPage:
 
     def click_modal_ok(self):
         time.sleep(0.5)
-        self.click_element(self.find_by_xpath("//button[contains(.,'OK')]"))
+        # Find active alertify dialog in case of multiple alertify dialog & click on that dialog
+        self.click_element(
+            self.find_by_xpath("//div[contains(@class, 'alertify') and not(contains(@class, 'ajs-hidden'))]//button[.='OK']")
+        )
 
     def add_server(self, server_config):
         self.find_by_xpath("//*[@class='aciTreeText' and contains(.,'Servers')]").click()
diff --git a/web/regression/python_test_utils/test_utils.py b/web/regression/python_test_utils/test_utils.py
index 5fa13a648..947bcf3a1 100644
--- a/web/regression/python_test_utils/test_utils.py
+++ b/web/regression/python_test_utils/test_utils.py
@@ -158,6 +158,83 @@ def create_table(server, db_name, table_name):
     except Exception:
         traceback.print_exc(file=sys.stderr)
 
+def create_constraint(
+        server, db_name, table_name,
+        constraint_type="unique", constraint_name="test_unique"):
+    try:
+        connection = get_db_connection(db_name,
+                                       server['username'],
+                                       server['db_password'],
+                                       server['host'],
+                                       server['port'])
+        old_isolation_level = connection.isolation_level
+        connection.set_isolation_level(0)
+        pg_cursor = connection.cursor()
+        pg_cursor.execute('''
+            ALTER TABLE "%s"
+              ADD CONSTRAINT "%s" %s (some_column)
+            ''' % (table_name, constraint_name, constraint_type.upper())
+        )
+
+        connection.set_isolation_level(old_isolation_level)
+        connection.commit()
+
+    except Exception:
+        traceback.print_exc(file=sys.stderr)
+
+def create_debug_function(server, db_name, function_name="test_func"):
+    try:
+        connection = get_db_connection(db_name,
+                                       server['username'],
+                                       server['db_password'],
+                                       server['host'],
+                                       server['port'])
+        old_isolation_level = connection.isolation_level
+        connection.set_isolation_level(0)
+        pg_cursor = connection.cursor()
+        pg_cursor.execute('''
+            CREATE OR REPLACE FUNCTION public."%s"()
+              RETURNS text
+                LANGUAGE 'plpgsql'
+                COST 100.0
+                VOLATILE
+            AS $function$
+              BEGIN
+                RAISE INFO 'This is a test function';
+                RAISE NOTICE '<img src="x" onerror="console.log(1)">';
+                RAISE NOTICE '<h1 onmouseover="console.log(1);">';
+                RETURN 'Hello, pgAdmin4';
+              END;
+            $function$;
+            ''' % (function_name)
+        )
+        connection.set_isolation_level(old_isolation_level)
+        connection.commit()
+
+    except Exception:
+        traceback.print_exc(file=sys.stderr)
+
+
+def drop_debug_function(server, db_name, function_name="test_func"):
+    try:
+        connection = get_db_connection(db_name,
+                                       server['username'],
+                                       server['db_password'],
+                                       server['host'],
+                                       server['port'])
+        old_isolation_level = connection.isolation_level
+        connection.set_isolation_level(0)
+        pg_cursor = connection.cursor()
+        pg_cursor.execute('''
+            DROP FUNCTION public."%s"();
+            ''' % (function_name)
+        )
+        connection.set_isolation_level(old_isolation_level)
+        connection.commit()
+
+    except Exception:
+        traceback.print_exc(file=sys.stderr)
+
 
 def drop_database(connection, database_name):
     """This function used to drop the database"""