diff --git a/src/Controller/UserSettingsController.php b/src/Controller/UserSettingsController.php
index 877d25f0..d97dbe78 100644
--- a/src/Controller/UserSettingsController.php
+++ b/src/Controller/UserSettingsController.php
@@ -79,6 +79,10 @@ public function add($user_id=null)
                 if (empty($currentUser['role']['perm_community_admin'])) {
                     $data['user_id'] = $currentUser->id;
                 }
+                $validationResult = $this->UserSettings->validateUserSetting($data, $currentUser);
+                if (!$validationResult !== true) {
+                    throw new MethodNotAllowedException(__('You cannot create the given user setting. Reason: {0}', $validationResult));
+                }
                 return $data;
             }
         ]);
@@ -131,6 +135,10 @@ public function edit($id)
                 if ($data['user_id'] != $entity->user_id) {
                     throw new MethodNotAllowedException(__('You cannot assign the setting to a different user.'));
                 }
+                $validationResult = $this->UserSettings->validateUserSetting($data);
+                if ($validationResult !== true) {
+                    throw new MethodNotAllowedException(__('Setting value: {0}', $validationResult));
+                }
                 return $data;
             }
         ]);
diff --git a/src/Model/Table/SettingProviders/CerebrateSettingsProvider.php b/src/Model/Table/SettingProviders/CerebrateSettingsProvider.php
index 256b3a96..39def17d 100644
--- a/src/Model/Table/SettingProviders/CerebrateSettingsProvider.php
+++ b/src/Model/Table/SettingProviders/CerebrateSettingsProvider.php
@@ -338,6 +338,17 @@ protected function generateSettingsConfiguration()
                         ],
                     ]
                 ],
+                'Restrictions' => [
+                    'Allowed bookmark domains' => [
+                        'security.restrictions.allowed_bookmark_domains' => [
+                            'name' => __('Allowed bookmark domains'),
+                            'type' => 'string',
+                            'severity' => 'info',
+                            'description' => __('Comma separated list of allowed bookmark domains. Leave empty to allow all domains.'),
+                            'default' => '',
+                        ],
+                    ],
+                ],
                 'Development' => [
                     'Debugging' => [
                         'debug' => [
diff --git a/src/Model/Table/UserSettingsTable.php b/src/Model/Table/UserSettingsTable.php
index 81cec2cf..0bbde9a4 100644
--- a/src/Model/Table/UserSettingsTable.php
+++ b/src/Model/Table/UserSettingsTable.php
@@ -5,6 +5,7 @@
 use App\Model\Table\AppTable;
 use Cake\ORM\Table;
 use Cake\Validation\Validator;
+use Cake\Core\Configure;
 
 require_once(APP . 'Model' . DS . 'Table' . DS . 'SettingProviders' . DS . 'UserSettingsProvider.php');
 use App\Settings\SettingsProvider\UserSettingsProvider;
@@ -102,6 +103,14 @@ public function saveBookmark($user, $data)
             'name' => $data['bookmark_name'],
             'url' => $data['bookmark_url'],
         ];
+        $restricted_domains = Configure::read('Security.restrictions.allowed_bookmark_domains');
+        if (!empty($restricted_domains)) {
+            $restricted_domains = explode(',', $restricted_domains);
+            $parsed = parse_url($bookmarkData['url']);
+            if (!in_array($parsed['host'], $restricted_domains)) {
+                return null;
+            }
+        }
         if (is_null($setting)) { // setting not found, create it
             $bookmarksData = json_encode([$bookmarkData]);
             $result = $this->createSetting($user, $this->BOOKMARK_SETTING_NAME, $bookmarksData);
@@ -153,4 +162,40 @@ public function validURI(String $uri): bool
         }
         return $isLocalPath || $isValidURL;
     }
+
+    public function validateUserSetting($data): bool|string
+    {
+        $errors = [];
+        $json_fields = ['ui.bookmarks'];
+        if (in_array($data['name'], $json_fields)) {
+            $decoded = json_decode($data['value'], true);
+            if (json_last_error() !== JSON_ERROR_NONE) {
+                return __('Invalid JSON data');
+            }
+            $value = $decoded;
+        } else {
+            $value = $data['value'];
+        }
+        if ($data['name'] === 'ui.bookmarks') {
+            if (array_values($value) !== $value) {
+                $value = [$value];
+            }
+            $restricted_domains = Configure::read('security.restrictions.allowed_bookmark_domains');
+            if (!empty($restricted_domains)) {
+                $restricted_domains = explode(',', $restricted_domains);
+                foreach ($restricted_domains as &$rd) {
+                    $rd = trim($rd);
+                }
+            }
+            foreach ($value as $bookmark) {   
+                if (!empty($restricted_domains)) {
+                    $parsed = parse_url($bookmark['url']);
+                    if (!in_array($parsed['host'], $restricted_domains)) {
+                        return __('Invalid domain for bookmark. The only domains allowed are: {0}', implode(', ', $restricted_domains));
+                    }
+                }
+            }
+        }
+        return true;
+    }
 }