fix: prevent ReDoS vulnerability in regex validation

lib/tools/Config.js

@@ -16,6 +16,10 @@ var Config = module.exports = {
     'max'    : 'The maximum of "%s" is %s, but now is %s',
     'min'    : 'The minimum of "%s" is %s, but now is %s'
   },
+  // Cache for compiled regex patterns to prevent ReDoS
+  _regexCache: {},
+  // Maximum input length for regex validation to prevent ReDoS
+  _maxRegexInputLength: 10000,
   /**
    * Schema definition.
    * @returns {exports|*}
@@ -182,9 +186,27 @@ Config._valid = function(key, value, sch){
   }
 
   // Verify RegExp if exists.
-  if (this._error(type == '[object String]' && sch.regex && !(new RegExp(sch.regex)).test(value),
-      'regex', key, sch.desc || ('should match ' + sch.regex))) {
-    return null;
+  if (type == '[object String]' && sch.regex) {
+    // Prevent ReDoS: limit input length
+    if (value && value.length > Config._maxRegexInputLength) {
+      if (this._error(true, 'regex', key, 'Input exceeds maximum length of ' + Config._maxRegexInputLength + ' characters')) {
+        return null;
+      }
+    }
+    // Cache compiled regex to prevent ReDoS and improve performance
+    if (!Config._regexCache[sch.regex]) {
+      try {
+        Config._regexCache[sch.regex] = new RegExp(sch.regex);
+      } catch (e) {
+        if (this._error(true, 'regex', key, 'Invalid regex pattern: ' + e.message)) {
+          return null;
+        }
+      }
+    }
+    if (this._error(!Config._regexCache[sch.regex].test(value),
+        'regex', key, sch.desc || ('should match ' + sch.regex))) {
+      return null;
+    }
   }
 
   // Verify maximum / minimum of Number value.