diff --git a/phpBB/phpbb/captcha/plugins/plugin_interface.php b/phpBB/phpbb/captcha/plugins/plugin_interface.php
new file mode 100644
index 0000000000..f40745db21
--- /dev/null
+++ b/phpBB/phpbb/captcha/plugins/plugin_interface.php
@@ -0,0 +1,42 @@
+<?php
+
+namespace phpbb\captcha\plugins;
+
+interface plugin_interface
+{
+	const CONFIRMATION_REGISTRATION = 1;
+	const CONFIRMATION_LOGIN = 2;
+
+	const CONFIRMATION_POST = 3;
+
+	const CONFIRMATION_REPORT = 4;
+
+
+	/**
+	 * Check if the plugin is available
+	 * @return bool True if the plugin is available, false if not
+	 */
+	public function is_available(): bool;
+
+	/**
+	 * Check if the plugin has a configuration
+	 *
+	 * @return bool True if the plugin has a configuration, false if not
+	 */
+	public function has_config(): bool;
+
+	/**
+	 * Get the name of the plugin, should be language variable
+	 *
+	 * @return string
+	 */
+	public static function get_name(): string;
+
+	/**
+	 * Display the captcha for the specified type
+	 *
+	 * @param int $type Type of captcha, should be one of the CONFIRMATION_* constants
+	 * @return void
+	 */
+	public function show(int $type): void;
+}
diff --git a/phpBB/phpbb/captcha/plugins/turnstile.php b/phpBB/phpbb/captcha/plugins/turnstile.php
new file mode 100644
index 0000000000..1388f33012
--- /dev/null
+++ b/phpBB/phpbb/captcha/plugins/turnstile.php
@@ -0,0 +1,93 @@
+<?php
+
+namespace phpbb\captcha\plugins;
+
+class turnstile extends captcha_abstract
+{
+	/** @var \phpbb\config\config */
+	protected $config;
+
+	public function __construct(\phpbb\config\config $config)
+	{
+		$this->config = $config;
+	}
+
+	public function is_available()
+	{
+		return ($this->config->offsetGet('captcha_turnstile_key') ?? false);
+	}
+
+	public function get_template()
+	{
+		return 'custom_captcha.html'; // Template file for displaying the CAPTCHA
+	}
+
+	public function execute()
+	{
+		// Perform any necessary initialization or setup
+	}
+
+	public function validate()
+	{
+		// Implement server-side validation logic here
+		// Example: Validate the submitted CAPTCHA value using Cloudflare API
+
+		// Your Cloudflare API credentials
+		$api_email = 'your_email@example.com';
+		$api_key = 'your_api_key';
+
+		// Cloudflare API endpoint for CAPTCHA verification
+		$endpoint = 'https://api.cloudflare.com/client/v4/captcha/validate';
+
+		// CAPTCHA data to be sent in the request
+		$data = [
+			'email' => $api_email,
+			'key' => $api_key,
+			'response' => $this->confirm_code
+		];
+
+		// Initialize cURL session
+		$ch = curl_init();
+
+		// Set cURL options
+		curl_setopt_array($ch, [
+			CURLOPT_URL => $endpoint,
+			CURLOPT_POST => true,
+			CURLOPT_POSTFIELDS => json_encode($data),
+			CURLOPT_HTTPHEADER => [
+				'Content-Type: application/json',
+				'Accept: application/json'
+			],
+			CURLOPT_RETURNTRANSFER => true
+		]);
+
+		// Execute the cURL request
+		$response = curl_exec($ch);
+
+		// Check for errors
+		if ($response === false) {
+			// Handle cURL error
+			curl_close($ch);
+			return false;
+		}
+
+		// Decode the JSON response
+		$result = json_decode($response, true);
+
+		// Check if the response indicates success
+		if (isset($result['success']) && $result['success'] === true) {
+			// CAPTCHA validation passed
+			curl_close($ch);
+			return true;
+		} else {
+			// CAPTCHA validation failed
+			curl_close($ch);
+			return false;
+		}
+	}
+
+	public function get_generator_class()
+	{
+		throw new \Exception('No generator class given.');
+	}
+}
\ No newline at end of file
diff --git a/tests/functional/fixtures/ext/foo/test_captcha/captcha/test_captcha.php b/tests/functional/fixtures/ext/foo/test_captcha/captcha/test_captcha.php
new file mode 100644
index 0000000000..fb8c6ed090
--- /dev/null
+++ b/tests/functional/fixtures/ext/foo/test_captcha/captcha/test_captcha.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace foo\test_captcha\captcha;
+
+class test_captcha extends \phpbb\captcha\plugins\captcha_abstract
+{
+
+	function get_generator_class()
+	{
+	}
+
+	public function init($type)
+	{
+	}
+
+	public function execute_demo()
+	{
+	}
+
+	public function execute()
+	{
+	}
+
+	public function validate()
+	{
+		return true;
+	}
+
+	public function is_solved()
+	{
+		return true;
+	}
+}
\ No newline at end of file
diff --git a/tests/functional/fixtures/ext/foo/test_captcha/composer.json b/tests/functional/fixtures/ext/foo/test_captcha/composer.json
new file mode 100644
index 0000000000..0ed4598df9
--- /dev/null
+++ b/tests/functional/fixtures/ext/foo/test_captcha/composer.json
@@ -0,0 +1,23 @@
+{
+	"name": "foo/test_captcha",
+	"type": "phpbb-extension",
+	"description": "Testing extension for having a working captcha plugin",
+	"homepage": "",
+	"version": "1.0.0",
+	"time": "2024-03-24 01:01:01",
+	"license": "GPL-2.0",
+	"authors": [{
+		"name": "phpBB Limited",
+		"homepage": "https://www.phpbb.com",
+		"role": "Developer"
+	}],
+	"require": {
+		"php": ">=8.1"
+	},
+	"extra": {
+		"display-name": "phpBB 4.0 Test Captcha",
+		"soft-require": {
+			"phpbb/phpbb": "4.0.*@dev"
+		}
+	}
+}
diff --git a/tests/functional/fixtures/ext/foo/test_captcha/config/services.yml b/tests/functional/fixtures/ext/foo/test_captcha/config/services.yml
new file mode 100644
index 0000000000..75cdf52270
--- /dev/null
+++ b/tests/functional/fixtures/ext/foo/test_captcha/config/services.yml
@@ -0,0 +1,5 @@
+services:
+  foo_test_captcha.captcha.test_captcha:
+    class: foo\test_captcha\captcha\test_captcha
+    tags:
+      - { name: captcha.plugins }