diff --git a/CHANGELOG.md b/CHANGELOG.md
index 473b57e3..4dbfe0df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # PrivateBin version history
 
 ## 2.0.3 (not yet released)
+* FIXED: Prevent arbitrary PHP file inclusion when enabling template switching
 * FIXED: Malicious filename can be used for self-XSS / HTML injection locally for users
 * FIXED: Unable to create a new paste from the cloned one when a JSON file attached (#1585)
 
@@ -46,7 +47,7 @@
 * FIXED: Page template scripts loading order (#1579)
 
 ## 1.7.7 (2025-06-28)
-* ADDED: Switching templates using the web ui (#1501)
+* ADDED: Switching templates using the web UI (#1501)
 * ADDED: Show file name and size on download page (#603)
 * CHANGED: Passing large data structures by reference to reduce memory consumption (#858)
 * CHANGED: Removed use of ctype functions and polyfill library for ctype
diff --git a/lib/Controller.php b/lib/Controller.php
index 3d316687..1d726da5 100644
--- a/lib/Controller.php
+++ b/lib/Controller.php
@@ -216,13 +216,17 @@ class Controller
     {
         $templates = $this->_conf->getKey('availabletemplates');
         $template  = $this->_conf->getKey('template');
+        if (!in_array($template, $templates, true)) {
+            $templates[] = $template;
+        }
         TemplateSwitcher::setAvailableTemplates($templates);
         TemplateSwitcher::setTemplateFallback($template);
 
-        // force default template, if template selection is disabled and a default is set
-        if (!$this->_conf->getKey('templateselection') && !empty($template)) {
-            $_COOKIE['template'] = $template;
-            setcookie('template', $template, array('SameSite' => 'Lax', 'Secure' => true));
+        // force default template, if template selection is disabled
+        if (!$this->_conf->getKey('templateselection') && array_key_exists('template', $_COOKIE)) {
+            unset($_COOKIE['template']); // ensure value is not re-used in template switcher
+            $expiredInAllTimezones = time() - 86400;
+            setcookie('template', '', array('expires' => $expiredInAllTimezones, 'SameSite' => 'Lax', 'Secure' => true));
         }
     }
 
diff --git a/lib/TemplateSwitcher.php b/lib/TemplateSwitcher.php
index 22c65b08..fa9fdb18 100644
--- a/lib/TemplateSwitcher.php
+++ b/lib/TemplateSwitcher.php
@@ -59,16 +59,13 @@ class TemplateSwitcher
     {
         if (self::isTemplateAvailable($template)) {
             self::$_templateFallback = $template;
-
-            if (!in_array($template, self::getAvailableTemplates())) {
-                // Add custom template to the available templates list
-                self::$_availableTemplates[] = $template;
-            }
+        } else {
+            error_log('failed to set "' . $template . '" as a fallback, it needs to be added to the list of `availabletemplates` in the configuration file');
         }
     }
 
     /**
-     * get currently loaded template
+     * get user selected template or fallback
      *
      * @access public
      * @static
@@ -76,8 +73,13 @@ class TemplateSwitcher
      */
     public static function getTemplate(): string
     {
-        $selectedTemplate = self::getSelectedByUserTemplate();
-        return $selectedTemplate ?? self::$_templateFallback;
+        if (array_key_exists('template', $_COOKIE)) {
+            $template = basename($_COOKIE['template']);
+            if (self::isTemplateAvailable($template)) {
+                return $template;
+            }
+        }
+        return self::$_templateFallback;
     }
 
     /**
@@ -101,32 +103,10 @@ class TemplateSwitcher
      */
     public static function isTemplateAvailable(string $template): bool
     {
-        $available = in_array($template, self::getAvailableTemplates());
-
-        if (!$available && !View::isBootstrapTemplate($template)) {
-            $path      = View::getTemplateFilePath($template);
-            $available = file_exists($path);
+        if (in_array($template, self::getAvailableTemplates(), true)) {
+            return true;
         }
-
-        return $available;
-    }
-
-    /**
-     * get the template selected by user
-     *
-     * @access private
-     * @static
-     * @return string|null
-     */
-    private static function getSelectedByUserTemplate(): ?string
-    {
-        $selectedTemplate    = null;
-        $templateCookieValue = $_COOKIE['template'] ?? '';
-
-        if (self::isTemplateAvailable($templateCookieValue)) {
-            $selectedTemplate = $templateCookieValue;
-        }
-
-        return $selectedTemplate;
+        error_log('template "' . $template . '" is not in the list of `availabletemplates` in the configuration file');
+        return false;
     }
 }
diff --git a/lib/View.php b/lib/View.php
index dd15e321..514ac2b1 100644
--- a/lib/View.php
+++ b/lib/View.php
@@ -49,39 +49,19 @@ class View
      */
     public function draw($template)
     {
-        $path = self::getTemplateFilePath($template);
-        if (!file_exists($path)) {
-            throw new Exception('Template ' . $template . ' not found!', 80);
+        $dir  = PATH . 'tpl' . DIRECTORY_SEPARATOR;
+        $file = substr($template, 0, 10) === 'bootstrap-' ? 'bootstrap' : $template;
+        $path = $dir . $file . '.php';
+        if (!is_file($path)) {
+            throw new Exception('Template ' . $template . ' not found in file ' . $path . '!', 80);
+        }
+        if (!in_array($path, glob($dir . '*.php', GLOB_NOSORT | GLOB_ERR), true)) {
+            throw new Exception('Template ' . $file . '.php not found in ' . $dir . '!', 81);
         }
         extract($this->_variables);
         include $path;
     }
 
-    /**
-     * Get template file path
-     *
-     * @access public
-     * @param  string $template
-     * @return string
-     */
-    public static function getTemplateFilePath(string $template): string
-    {
-        $file = self::isBootstrapTemplate($template) ? 'bootstrap' : $template;
-        return PATH . 'tpl' . DIRECTORY_SEPARATOR . $file . '.php';
-    }
-
-    /**
-     * Is the template a variation of the bootstrap template
-     *
-     * @access public
-     * @param  string $template
-     * @return bool
-     */
-    public static function isBootstrapTemplate(string $template): bool
-    {
-        return substr($template, 0, 10) === 'bootstrap-';
-    }
-
     /**
      * echo script tag incl. SRI hash for given script file
      *
diff --git a/tst/Bootstrap.php b/tst/Bootstrap.php
index 5c5ceb6f..e905312c 100644
--- a/tst/Bootstrap.php
+++ b/tst/Bootstrap.php
@@ -6,7 +6,9 @@ use Google\Cloud\Storage\Bucket;
 use Google\Cloud\Storage\Connection\ConnectionInterface;
 use Google\Cloud\Storage\StorageClient;
 use Google\Cloud\Storage\StorageObject;
+use PrivateBin\Configuration;
 use PrivateBin\Persistence\ServerSalt;
+use PrivateBin\TemplateSwitcher;
 
 error_reporting(E_ALL | E_STRICT);
 
@@ -26,6 +28,7 @@ if (!defined('CONF_SAMPLE')) {
 
 require PATH . 'vendor/autoload.php';
 Helper::updateSubresourceIntegrity();
+TemplateSwitcher::setAvailableTemplates(Configuration::getDefaults()['main']['availabletemplates']);
 
 /**
  * Class Helper provides unit tests pastes and comments of various formats
diff --git a/tst/TemplateSwitcherTest.php b/tst/TemplateSwitcherTest.php
index 16aec6b0..7f4ef8d8 100644
--- a/tst/TemplateSwitcherTest.php
+++ b/tst/TemplateSwitcherTest.php
@@ -41,6 +41,7 @@ class TemplateSwitcherTest extends TestCase
         $defaultTemplateFallback = 'bootstrap5';
         $customTemplate          = 'bootstrap-dark';
         $customWrongTemplate     = 'bootstrap-wrong';
+        $escapeTemplateDirectory = '../index';
 
         TemplateSwitcher::setTemplateFallback($defaultTemplateFallback);
 
@@ -49,6 +50,9 @@ class TemplateSwitcherTest extends TestCase
 
         $_COOKIE['template'] = $customTemplate;
         $this->assertEquals($customTemplate, TemplateSwitcher::getTemplate(), 'Custom template');
+
+        $_COOKIE['template'] = $escapeTemplateDirectory;
+        $this->assertEquals($defaultTemplateFallback, TemplateSwitcher::getTemplate(), 'Fallback on escaping template directory');
     }
 
     public function testGetAvailableTemplates()
diff --git a/tst/ViewTest.php b/tst/ViewTest.php
index fcb0bdac..b3d4aa37 100644
--- a/tst/ViewTest.php
+++ b/tst/ViewTest.php
@@ -142,19 +142,12 @@ class ViewTest extends TestCase
         $test->draw('123456789 does not exist!');
     }
 
-    public function testTemplateFilePath()
+    public function testInvalidTemplate()
     {
-        $template     = 'bootstrap';
-        $templatePath = PATH . 'tpl' . DIRECTORY_SEPARATOR . $template . '.php';
-        $path         = View::getTemplateFilePath($template);
-        $this->assertEquals($templatePath, $path, 'Template file path');
+        $test = new View;
+        $this->expectException(Exception::class);
+        $this->expectExceptionCode(81);
+        $test->draw('../index');
     }
 
-    public function testIsBootstrapTemplate()
-    {
-        $bootstrapTemplate    = 'bootstrap-dark';
-        $nonBootstrapTemplate = 'bootstrap5';
-        $this->assertTrue(View::isBootstrapTemplate($bootstrapTemplate), 'Is bootstrap template');
-        $this->assertFalse(View::isBootstrapTemplate($nonBootstrapTemplate), 'Is not bootstrap template');
-    }
 }