diff --git a/.env.example b/.env.example
index 86b7fc1e20..3bc9575414 100644
--- a/.env.example
+++ b/.env.example
@@ -80,3 +80,7 @@ KEYCLOAK_CLIENT_SECRET=
 KEYCLOAK_BASE_URL=
 KEYCLOAK_USERNAME=
 KEYCLOAK_PASSWORD=
+
+# Comma-separated file extensions (optional; defaults in config/files.php)
+# ALLOWED_EXTENSIONS=pdf,doc,docx,txt,jpg,png
+# DANGEROUS_EXTENSIONS=zip,rar,7z,tar
diff --git a/config/files.php b/config/files.php
index d95f373047..23f99063ea 100644
--- a/config/files.php
+++ b/config/files.php
@@ -1,5 +1,38 @@
 <?php
 
+$parseCommaSeparatedExtensions = static function (string $envKey, array $default): array {
+    $value = env($envKey);
+
+    if (!is_string($value) || trim($value) === '') {
+        return $default;
+    }
+
+    return array_values(array_filter(array_map(
+        static fn (string $extension) => strtolower(trim($extension)),
+        explode(',', $value)
+    )));
+};
+
+$defaultAllowedExtensions = [
+    // Documents
+    'pdf', 'doc', 'docx', 'xls', 'xlsx', 'ppt', 'pptx',
+    'txt', 'csv',
+
+    // Images
+    'jpg', 'jpeg', 'png', 'gif', 'svg',
+
+    // Audio
+    'mp3',
+
+    // Video
+    'mp4', 'webm',
+];
+
+$defaultDangerousExtensions = [
+    'zip', 'rar', '7z', 'tar', 'gz', 'bz2', 'xz', 'lzma',
+    'cab', 'ar', 'iso', 'dmg', 'pkg', 'deb', 'rpm',
+];
+
 return [
     /*
     |--------------------------------------------------------------------------
@@ -19,22 +52,13 @@
     | List of file extensions that are allowed to be uploaded.
     | Only files with these extensions will be accepted.
     | Archive formats (.zip, .rar, .tar, .7z) are explicitly NOT allowed for security.
+    | Override with comma-separated ALLOWED_EXTENSIONS in .env (optional).
     |
     */
-    'allowed_extensions' => [
-        // Documents
-        'pdf', 'doc', 'docx', 'xls', 'xlsx', 'ppt', 'pptx',
-        'txt', 'csv',
-
-        // Images
-        'jpg', 'jpeg', 'png', 'gif', 'svg',
-
-        // Audio
-        'mp3',
-
-        // Video
-        'mp4', 'webm',
-    ],
+    'allowed_extensions' => $parseCommaSeparatedExtensions(
+        'ALLOWED_EXTENSIONS',
+        $defaultAllowedExtensions
+    ),
     /*
     |--------------------------------------------------------------------------
     | Extension to MIME Type Mapping
@@ -116,12 +140,13 @@
     | Archive formats (.zip, .rar, .tar, .7z, .gz, etc.) are explicitly
     | NOT allowed for security reasons. These file types can contain
     | malicious content and are blocked by default.
+    | Override with comma-separated DANGEROUS_EXTENSIONS in .env (optional).
     |
     */
-    'dangerous_extensions' => [
-        'zip', 'rar', '7z', 'tar', 'gz', 'bz2', 'xz', 'lzma',
-        'cab', 'ar', 'iso', 'dmg', 'pkg', 'deb', 'rpm',
-    ],
+    'dangerous_extensions' => $parseCommaSeparatedExtensions(
+        'DANGEROUS_EXTENSIONS',
+        $defaultDangerousExtensions
+    ),
 
     /*
     |--------------------------------------------------------------------------
diff --git a/tests/unit/FilesConfigTest.php b/tests/unit/FilesConfigTest.php
new file mode 100644
index 0000000000..a338d84a2f
--- /dev/null
+++ b/tests/unit/FilesConfigTest.php
@@ -0,0 +1,85 @@
+<?php
+
+namespace Tests\Unit;
+
+use PHPUnit\Framework\TestCase;
+
+class FilesConfigTest extends TestCase
+{
+    private const ENV_ALLOWED = 'ALLOWED_EXTENSIONS';
+
+    private const ENV_DANGEROUS = 'DANGEROUS_EXTENSIONS';
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        if (!function_exists('env')) {
+            require_once __DIR__ . '/../../vendor/laravel/framework/src/Illuminate/Foundation/helpers.php';
+        }
+    }
+
+    protected function tearDown(): void
+    {
+        $this->unsetEnv(self::ENV_ALLOWED);
+        $this->unsetEnv(self::ENV_DANGEROUS);
+
+        parent::tearDown();
+    }
+
+    public function test_allowed_extensions_use_defaults_when_env_unset(): void
+    {
+        $this->unsetEnv(self::ENV_ALLOWED);
+
+        $config = $this->loadFilesConfig();
+
+        $this->assertContains('pdf', $config['allowed_extensions']);
+        $this->assertContains('mp4', $config['allowed_extensions']);
+    }
+
+    public function test_allowed_extensions_parsed_from_env(): void
+    {
+        $this->setEnv(self::ENV_ALLOWED, 'pdf, custom ,TXT');
+
+        $config = $this->loadFilesConfig();
+
+        $this->assertSame(['pdf', 'custom', 'txt'], $config['allowed_extensions']);
+    }
+
+    public function test_dangerous_extensions_parsed_from_env(): void
+    {
+        $this->setEnv(self::ENV_DANGEROUS, 'zip,rar');
+
+        $config = $this->loadFilesConfig();
+
+        $this->assertSame(['zip', 'rar'], $config['dangerous_extensions']);
+    }
+
+    public function test_dangerous_extensions_defaults_when_env_empty(): void
+    {
+        $this->unsetEnv(self::ENV_DANGEROUS);
+
+        $config = $this->loadFilesConfig();
+
+        $this->assertContains('zip', $config['dangerous_extensions']);
+        $this->assertContains('7z', $config['dangerous_extensions']);
+    }
+
+    private function loadFilesConfig(): array
+    {
+        return include __DIR__ . '/../../config/files.php'; // NOSONAR: load fresh config after changing environment variables.
+    }
+
+    private function setEnv(string $key, string $value): void
+    {
+        putenv("{$key}={$value}");
+        $_ENV[$key] = $value;
+        $_SERVER[$key] = $value;
+    }
+
+    private function unsetEnv(string $key): void
+    {
+        putenv($key);
+        unset($_ENV[$key], $_SERVER[$key]);
+    }
+}