Path Traversal allowing arbitrary read of files in Yeswiki

@@ -119,31 +119,74 @@ public function loadTemplates($metadata = []): ?array
             $this->setFavorite('preset', $this->getConfigAsStringOrDefault('favorite_preset', ''));
         } else {
             // Sinon, on récupère premièrement les valeurs passées en REQUEST, ou deuxièmement les métasdonnées présentes pour la page, ou troisièmement les valeurs du fichier de configuration
-            if (isset($_REQUEST['theme']) && (is_dir('custom/themes/' . $_REQUEST['theme']) || is_dir('themes/' . $_REQUEST['theme']))
-                && isset($_REQUEST['style']) && (is_file('custom/themes/' . $_REQUEST['theme'] . '/styles/' . $_REQUEST['style']) || is_file('themes/' . $_REQUEST['theme'] . '/styles/' . $_REQUEST['style']))
-                && isset($_REQUEST['squelette']) && (is_file('custom/themes/' . $_REQUEST['theme'] . '/squelettes/' . $_REQUEST['squelette']) || is_file('themes/' . $_REQUEST['theme'] . '/squelettes/' . $_REQUEST['squelette']))
+            $requested = [];
+            $keysToVerify = ['theme', 'squelette', 'style', 'preset'];
+            foreach ($keysToVerify as $val) {
+                $requested[$val] = null;
+                if (!empty($_REQUEST[$val])) {
+                    if (preg_match('/\//', $_REQUEST[$val], $matches)) {
+                        exit('ERROR: Suspicious path traversal attempt.');
+                    }
+                    switch ($val) {
+                        case 'theme':
+                            $customThemePath = basename(realpath(getcwd() . '/custom/themes/' . $_REQUEST[$val]));
+                            $classicThemePath = basename(realpath(getcwd() . '/themes/' . $_REQUEST[$val]));
+                            $requested[$val] = !empty($customThemePath) ? $customThemePath : $classicThemePath;
+                            break;
+
+                        case 'squelette':
+                            $customPath = basename(realpath(getcwd() . '/custom/themes/' . $requested['theme'] . '/squelettes/' . $_REQUEST[$val]));
+                            $classicPath = basename(realpath(getcwd() . '/themes/' . $requested['theme'] . 'squelettes/' . $_REQUEST[$val]));
+                            $requested[$val] = null;
+                            if (!empty($customPath) && file_exists(getcwd() . '/custom/themes/' . $requested['theme'] . '/squelettes/' . $customPath)) {
+                                $requested[$val] = $customPath;
+                            } elseif (file_exists(getcwd() . '/themes/' . $requested['theme'] . '/squelettes/' . $classicPath)) {
+                                $requested[$val] = $classicPath;
+                            }
+                            if (!preg_match('/\.tpl\.html$/i', $requested[$val] ?? '', $matches)) {
+                                $requested[$val] = null;
+                            }
+
+                            break;
+
+                        default:
+                            // ugly append of "s" to get the path of styleS, presetS and squeletteS
+                            $customPath = basename(realpath(getcwd() . '/custom/themes/' . $requested['theme'] . '/' . $val . 's/' . $_REQUEST[$val]));
+                            $classicPath = basename(realpath(getcwd() . '/themes/' . $requested['theme'] . '/' . $val . 's/' . $_REQUEST[$val]));
+                            $requested[$val] = null;
+                            if (!empty($customPath) && file_exists(getcwd() . '/custom/themes/' . $requested['theme'] . '/' . $val . 's/' . $customPath)) {
+                                $requested[$val] = $customPath;
+                            } elseif (file_exists(getcwd() . '/themes/' . $requested['theme'] . '/' . $val . 's/' . $classicPath)) {
+                                $requested[$val] = $classicPath;
+                            }
+
+                            break;
+                    }
+                }
+            }
+            if (!empty($requested['theme']) && !empty($requested['style']) && !empty($requested['squelette']) && preg_match('/\.tpl\.html$/i', $requested['squelette'], $matches)
             ) {
-                $this->setFavorite('theme', $_REQUEST['theme']);
-                $this->setFavorite('style', $_REQUEST['style']);
-                $this->setFavorite('squelette', $_REQUEST['squelette']);
+                $this->setFavorite('theme', $requested['theme']);
+                $this->setFavorite('style', $requested['style']);
+                $this->setFavorite('squelette', $requested['squelette']);
 
                 // presets
-                if (isset($_REQUEST['preset'])
+                if (!empty($requested['preset'])
                         && (
                             (
-                                ($isCustom = (substr($_REQUEST['preset'], 0, strlen(self::CUSTOM_CSS_PRESETS_PREFIX)) == self::CUSTOM_CSS_PRESETS_PREFIX))
-                                && is_file(self::CUSTOM_CSS_PRESETS_PATH . '/' . substr($_REQUEST['preset'], strlen(self::CUSTOM_CSS_PRESETS_PREFIX)))
+                                ($isCustom = (substr($requested['preset'], 0, strlen(self::CUSTOM_CSS_PRESETS_PREFIX)) == self::CUSTOM_CSS_PRESETS_PREFIX))
+                                && is_file(self::CUSTOM_CSS_PRESETS_PATH . '/' . substr($requested['preset'], strlen(self::CUSTOM_CSS_PRESETS_PREFIX)))
                             )
                             || (
                                 !$isCustom
                                 && (
-                                    is_file('custom/themes/' . $_REQUEST['theme'] . '/presets/' . $_REQUEST['preset'])
-                                    || is_file('themes/' . $_REQUEST['theme'] . '/presets/' . $_REQUEST['preset'])
+                                    is_file('custom/themes/' . $requested['theme'] . '/presets/' . $requested['preset'])
+                                    || is_file('themes/' . $requested['theme'] . '/presets/' . $requested['preset'])
                                 )
                             )
                         )
                 ) {
-                    $this->setFavorite('preset', $_REQUEST['preset']);
+                    $this->setFavorite('preset', $requested['preset']);
                 }
 
                 if (isset($_REQUEST['bgimg']) && is_file('files/backgrounds/' . $_REQUEST['bgimg'])) {