diff --git a/phpBB/composer.json b/phpBB/composer.json
index d5acd3112c..72d074e15d 100644
--- a/phpBB/composer.json
+++ b/phpBB/composer.json
@@ -44,6 +44,7 @@
 		"symfony/finder": "~3.4",
 		"symfony/http-foundation": "~3.4",
 		"symfony/http-kernel": "~3.4",
+		"symfony/polyfill-intl-idn": "~1.17.0",
 		"symfony/process": "^3.4",
 		"symfony/proxy-manager-bridge": "~3.4",
 		"symfony/routing": "~3.4",
diff --git a/phpBB/composer.lock b/phpBB/composer.lock
index bd5be6ce7d..4193f9cd8e 100644
--- a/phpBB/composer.lock
+++ b/phpBB/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "0c76d2f8642ebab8e5d300715d1c05bc",
+    "content-hash": "53d2ea724fccfc1954604ca3d2d5a3df",
     "packages": [
         {
             "name": "bantu/ini-get-wrapper",
@@ -517,20 +517,20 @@
         },
         {
             "name": "paragonie/random_compat",
-            "version": "v9.99.99",
+            "version": "v9.99.100",
             "source": {
                 "type": "git",
                 "url": "https://github.com/paragonie/random_compat.git",
-                "reference": "84b4dfb120c6f9b4ff7b3685f9b8f1aa365a0c95"
+                "reference": "996434e5492cb4c3edcb9168db6fbb1359ef965a"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/paragonie/random_compat/zipball/84b4dfb120c6f9b4ff7b3685f9b8f1aa365a0c95",
-                "reference": "84b4dfb120c6f9b4ff7b3685f9b8f1aa365a0c95",
+                "url": "https://api.github.com/repos/paragonie/random_compat/zipball/996434e5492cb4c3edcb9168db6fbb1359ef965a",
+                "reference": "996434e5492cb4c3edcb9168db6fbb1359ef965a",
                 "shasum": ""
             },
             "require": {
-                "php": "^7"
+                "php": ">= 7"
             },
             "require-dev": {
                 "phpunit/phpunit": "4.*|5.*",
@@ -558,7 +558,7 @@
                 "pseudorandom",
                 "random"
             ],
-            "time": "2018-07-02T15:55:56+00:00"
+            "time": "2020-10-15T08:29:30+00:00"
         },
         {
             "name": "patchwork/utf8",
@@ -1730,22 +1730,21 @@
         },
         {
             "name": "symfony/polyfill-intl-idn",
-            "version": "v1.18.1",
+            "version": "v1.17.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-intl-idn.git",
-                "reference": "5dcab1bc7146cf8c1beaa4502a3d9be344334251"
+                "reference": "a57f8161502549a742a63c09f0a604997bf47027"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-intl-idn/zipball/5dcab1bc7146cf8c1beaa4502a3d9be344334251",
-                "reference": "5dcab1bc7146cf8c1beaa4502a3d9be344334251",
+                "url": "https://api.github.com/repos/symfony/polyfill-intl-idn/zipball/a57f8161502549a742a63c09f0a604997bf47027",
+                "reference": "a57f8161502549a742a63c09f0a604997bf47027",
                 "shasum": ""
             },
             "require": {
                 "php": ">=5.3.3",
-                "symfony/polyfill-intl-normalizer": "^1.10",
-                "symfony/polyfill-php70": "^1.10",
+                "symfony/polyfill-mbstring": "^1.3",
                 "symfony/polyfill-php72": "^1.10"
             },
             "suggest": {
@@ -1754,7 +1753,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.18-dev"
+                    "dev-master": "1.17-dev"
                 },
                 "thanks": {
                     "name": "symfony/polyfill",
@@ -1778,10 +1777,6 @@
                     "name": "Laurent Bassin",
                     "email": "laurent@bassin.info"
                 },
-                {
-                    "name": "Trevor Rowbotham",
-                    "email": "trevor.rowbotham@pm.me"
-                },
                 {
                     "name": "Symfony Community",
                     "homepage": "https://symfony.com/contributors"
@@ -1811,88 +1806,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2020-08-04T06:02:08+00:00"
-        },
-        {
-            "name": "symfony/polyfill-intl-normalizer",
-            "version": "v1.18.1",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/symfony/polyfill-intl-normalizer.git",
-                "reference": "37078a8dd4a2a1e9ab0231af7c6cb671b2ed5a7e"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-intl-normalizer/zipball/37078a8dd4a2a1e9ab0231af7c6cb671b2ed5a7e",
-                "reference": "37078a8dd4a2a1e9ab0231af7c6cb671b2ed5a7e",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.3.3"
-            },
-            "suggest": {
-                "ext-intl": "For best performance"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.18-dev"
-                },
-                "thanks": {
-                    "name": "symfony/polyfill",
-                    "url": "https://github.com/symfony/polyfill"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Symfony\\Polyfill\\Intl\\Normalizer\\": ""
-                },
-                "files": [
-                    "bootstrap.php"
-                ],
-                "classmap": [
-                    "Resources/stubs"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Nicolas Grekas",
-                    "email": "p@tchwork.com"
-                },
-                {
-                    "name": "Symfony Community",
-                    "homepage": "https://symfony.com/contributors"
-                }
-            ],
-            "description": "Symfony polyfill for intl's Normalizer class and related functions",
-            "homepage": "https://symfony.com",
-            "keywords": [
-                "compatibility",
-                "intl",
-                "normalizer",
-                "polyfill",
-                "portable",
-                "shim"
-            ],
-            "funding": [
-                {
-                    "url": "https://symfony.com/sponsor",
-                    "type": "custom"
-                },
-                {
-                    "url": "https://github.com/fabpot",
-                    "type": "github"
-                },
-                {
-                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
-                    "type": "tidelift"
-                }
-            ],
-            "time": "2020-07-14T12:35:20+00:00"
+            "time": "2020-06-06T08:46:27+00:00"
         },
         {
             "name": "symfony/polyfill-mbstring",