diff --git a/src/Command/CheckRequirementsCommand.php b/src/Command/CheckRequirementsCommand.php
index f9080c42..fac928b2 100644
--- a/src/Command/CheckRequirementsCommand.php
+++ b/src/Command/CheckRequirementsCommand.php
@@ -22,6 +22,7 @@ declare(strict_types=1);
  */
 namespace App\Command;
 
+use App\Services\System\AppSecretChecker;
 use Symfony\Component\Console\Attribute\AsCommand;
 use Symfony\Component\Console\Command\Command;
 use Symfony\Component\Console\Input\InputInterface;
@@ -33,7 +34,9 @@ use Symfony\Component\DependencyInjection\ParameterBag\ContainerBagInterface;
 #[AsCommand('partdb:check-requirements', 'Checks if the requirements Part-DB needs or recommends are fulfilled.')]
 class CheckRequirementsCommand extends Command
 {
-    public function __construct(protected ContainerBagInterface $params)
+    public function __construct(protected ContainerBagInterface $params, AppSecretChecker $secretChecker,
+        private readonly AppSecretChecker $appSecretChecker
+    )
     {
         parent::__construct();
     }
@@ -121,6 +124,16 @@ class CheckRequirementsCommand extends Command
             $io->success('Debug mode disabled.');
         }
 
+        //Check if APP_SECRET has been changed from the default
+        if ($io->isVerbose()) {
+            $io->comment('Checking APP_SECRET...');
+        }
+        if ($this->appSecretChecker->isInsecureSecret()) {
+            $io->warning('APP_SECRET is set to the default value shipped with Part-DB. This is a security risk! Generate a new secret (e.g. using "openssl rand -hex 32") and set it as APP_SECRET in your .env.local file.');
+        } elseif (!$only_issues) {
+            $io->success('APP_SECRET has been changed from the default value.');
+        }
+
     }
 
     protected function checkPHPExtensions(SymfonyStyle $io, bool $only_issues = false): void
diff --git a/src/Controller/HomepageController.php b/src/Controller/HomepageController.php
index 6f863a3c..f64f281f 100644
--- a/src/Controller/HomepageController.php
+++ b/src/Controller/HomepageController.php
@@ -24,6 +24,7 @@ namespace App\Controller;
 
 use App\DataTables\LogDataTable;
 use App\Entity\Parts\Part;
+use App\Services\System\AppSecretChecker;
 use App\Services\System\BannerHelper;
 use App\Services\System\GitVersionInfoProvider;
 use App\Services\System\UpdateAvailableFacade;
@@ -36,8 +37,11 @@ use Symfony\Component\Routing\Attribute\Route;
 
 class HomepageController extends AbstractController
 {
-    public function __construct(private readonly DataTableFactory $dataTable, private readonly BannerHelper $bannerHelper)
-    {
+    public function __construct(
+        private readonly DataTableFactory $dataTable,
+        private readonly BannerHelper $bannerHelper,
+        private readonly AppSecretChecker $appSecretChecker,
+    ) {
     }
 
 
@@ -84,6 +88,8 @@ class HomepageController extends AbstractController
             'new_version_available' => $updateAvailableManager->isUpdateAvailable(),
             'new_version' => $updateAvailableManager->getLatestVersionString(),
             'new_version_url' => $updateAvailableManager->getLatestVersionUrl(),
+            'insecure_app_secret' => $this->appSecretChecker->isInsecureSecret(),
+            'suggested_app_secret' => $this->appSecretChecker->isInsecureSecret() ? $this->appSecretChecker->generateSecret() : null,
         ]);
     }
 }
diff --git a/src/Services/System/AppSecretChecker.php b/src/Services/System/AppSecretChecker.php
new file mode 100644
index 00000000..d5a29ba5
--- /dev/null
+++ b/src/Services/System/AppSecretChecker.php
@@ -0,0 +1,62 @@
+<?php
+/*
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ *  Copyright (C) 2019 - 2024 Jan Böhmer (https://github.com/jbtronics)
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as published
+ *  by the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace App\Services\System;
+
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
+
+/**
+ * Checks whether APP_SECRET has been changed from the default value shipped with Part-DB.
+ */
+final readonly class AppSecretChecker
+{
+    /** Known default/example secrets that must not be used in production. */
+    public const INSECURE_SECRETS = [
+        'a03498528f5a5fc089273ec9ae5b2849', // default in .env
+        '318b5d659e07a0b3f96d9b3a83b254ca', // default in .env.dev
+    ];
+
+    public function __construct(
+        #[Autowire('%kernel.secret%')]
+        private string $appSecret,
+    ) {
+    }
+
+    /**
+     * @return bool True if the app secret is one of the known insecure default secrets, false otherwise.
+     */
+    public function isInsecureSecret(): bool
+    {
+        return in_array($this->appSecret, self::INSECURE_SECRETS, true);
+    }
+
+    /**
+     * Generates a new random app secret that can be used to replace the default insecure one.
+     * @return string
+     * @throws \Random\RandomException
+     */
+    public function generateSecret(): string
+    {
+        //Symfony docs recommend 32 characters for the app secret, which are 16 random bytes when hex-encoded.
+        return bin2hex(random_bytes(16));
+    }
+}
diff --git a/templates/homepage.html.twig b/templates/homepage.html.twig
index 6e7aa360..d6b3a516 100644
--- a/templates/homepage.html.twig
+++ b/templates/homepage.html.twig
@@ -85,6 +85,15 @@
 
 {% block content %}
 
+    {% if insecure_app_secret and is_granted('@system.server_infos') %}
+        <div class="alert alert-warning" role="alert">
+            <h5><i class="fa-solid fa-triangle-exclamation fa-fw"></i> {% trans %}system.app_secret.insecure.title{% endtrans %}</h5>
+            <p class="mb-1">{% trans %}system.app_secret.insecure.message{% endtrans %}</p>
+            <p class="mb-0">{% trans %}system.app_secret.insecure.suggestion{% endtrans %}
+                <br><code>APP_SECRET={{ suggested_app_secret }}</code></p>
+        </div>
+    {% endif %}
+
     {% if is_granted('@system.show_updates') %}
         {{ nv.new_version_alert(new_version_available, new_version, new_version_url) }}
     {% endif %}
diff --git a/translations/messages.en.xlf b/translations/messages.en.xlf
index 11dcbd8e..60d48973 100644
--- a/translations/messages.en.xlf
+++ b/translations/messages.en.xlf
@@ -13649,5 +13649,23 @@ Buerklin-API Authentication server:
         <target>When enabled users with the info provider permission can submit pages to Part-DB and retrieve them later.</target>
       </segment>
     </unit>
+    <unit id="JqcvhX_" name="system.app_secret.insecure.title">
+      <segment state="translated">
+        <source>system.app_secret.insecure.title</source>
+        <target>Insecure APP_SECRET</target>
+      </segment>
+    </unit>
+    <unit id="XSSYWTJ" name="system.app_secret.insecure.message">
+      <segment state="translated">
+        <source>system.app_secret.insecure.message</source>
+        <target>APP_SECRET is set to the default value shipped with Part-DB. This is a security risk! Set it to a new random value in your .env.local or docker-compose.yaml file.</target>
+      </segment>
+    </unit>
+    <unit id="e7.f3m0" name="system.app_secret.insecure.suggestion">
+      <segment state="translated">
+        <source>system.app_secret.insecure.suggestion</source>
+        <target>You can use this randomly generated value (share it with nobody):</target>
+      </segment>
+    </unit>
   </file>
 </xliff>