diff --git a/composer.lock b/composer.lock
index e30fe37532d..e51f6c0bcc8 100644
--- a/composer.lock
+++ b/composer.lock
@@ -653,7 +653,7 @@
             "dist": {
                 "type": "path",
                 "url": "core",
-                "reference": "98e264668acbc33027a30953a7e194715b3ce33f"
+                "reference": "9faae700fd9adfe0a1c5ffd73dcc334b3be5ce5a"
             },
             "require": {
                 "asm89/stack-cors": "^1.1",
@@ -697,7 +697,7 @@
                 "symfony/yaml": "^4.4",
                 "twig/twig": "^1.38.2",
                 "typo3/phar-stream-wrapper": "^3.1.3",
-                "zendframework/zend-diactoros": ">=1.7 <1.8",
+                "zendframework/zend-diactoros": "^1.8",
                 "zendframework/zend-feed": "^2.12"
             },
             "conflict": {
@@ -3637,16 +3637,16 @@
         },
         {
             "name": "zendframework/zend-diactoros",
-            "version": "1.7.2",
+            "version": "1.8.7",
             "source": {
                 "type": "git",
                 "url": "https://github.com/zendframework/zend-diactoros.git",
-                "reference": "741e7a571836f038de731105f4742ca8a164e43a"
+                "reference": "a85e67b86e9b8520d07e6415fcbcb8391b44a75b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/zendframework/zend-diactoros/zipball/741e7a571836f038de731105f4742ca8a164e43a",
-                "reference": "741e7a571836f038de731105f4742ca8a164e43a",
+                "url": "https://api.github.com/repos/zendframework/zend-diactoros/zipball/a85e67b86e9b8520d07e6415fcbcb8391b44a75b",
+                "reference": "a85e67b86e9b8520d07e6415fcbcb8391b44a75b",
                 "shasum": ""
             },
             "require": {
@@ -3659,18 +3659,27 @@
             "require-dev": {
                 "ext-dom": "*",
                 "ext-libxml": "*",
-                "phpunit/phpunit": "^5.7.16 || ^6.0.8",
+                "php-http/psr7-integration-tests": "dev-master",
+                "phpunit/phpunit": "^5.7.16 || ^6.0.8 || ^7.2.7",
                 "zendframework/zend-coding-standard": "~1.0"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.7.x-dev",
-                    "dev-develop": "1.8.x-dev",
-                    "dev-release-2.0": "2.0.x-dev"
+                    "dev-release-1.8": "1.8.x-dev"
                 }
             },
             "autoload": {
+                "files": [
+                    "src/functions/create_uploaded_file.php",
+                    "src/functions/marshal_headers_from_sapi.php",
+                    "src/functions/marshal_method_from_sapi.php",
+                    "src/functions/marshal_protocol_version_from_sapi.php",
+                    "src/functions/marshal_uri_from_sapi.php",
+                    "src/functions/normalize_server.php",
+                    "src/functions/normalize_uploaded_files.php",
+                    "src/functions/parse_cookie_header.php"
+                ],
                 "psr-4": {
                     "Zend\\Diactoros\\": "src/"
                 }
@@ -3686,7 +3695,7 @@
                 "psr",
                 "psr-7"
             ],
-            "time": "2018-05-29T16:53:08+00:00"
+            "time": "2019-08-06T17:53:53+00:00"
         },
         {
             "name": "zendframework/zend-escaper",
diff --git a/core/composer.json b/core/composer.json
index d0f8f39a1cf..392bbe073a9 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -43,7 +43,7 @@
         "egulias/email-validator": "^2.0",
         "masterminds/html5": "^2.1",
         "symfony/psr-http-message-bridge": "^1.2.0",
-        "zendframework/zend-diactoros": ">=1.7 <1.8",
+        "zendframework/zend-diactoros": "^1.8",
         "composer/semver": "^1.0",
         "asm89/stack-cors": "^1.1",
         "pear/archive_tar": "^1.4.8"