diff --git a/backend/middleware/security.js b/backend/middleware/security.js
index 5266d1f..e0749cf 100644
--- a/backend/middleware/security.js
+++ b/backend/middleware/security.js
@@ -116,10 +116,17 @@ function apiKeyGuard(req, res, next) {
   if (p === '/api/health' || p.startsWith('/api/install')) return next();
   const key = getApiKey();
   if (!key) return next();
-  if (req.headers['x-api-key'] !== key) return res.status(401).json({ error: '无效的 API 密钥' });
+  if (!req.headers['x-api-key'] || req.headers['x-api-key'].length !== key.length) return res.status(401).json({ error: '无效的 API 密钥' });
+  if (!timingSafeEqual(req.headers['x-api-key'], key)) return res.status(401).json({ error: '无效的 API 密钥' });
   next();
 }
 
+function timingSafeEqual(a, b) {
+  let diff = a.length ^ b.length;
+  for (let i = 0; i < a.length; i++) diff |= a.charCodeAt(i) ^ b.charCodeAt(i);
+  return diff === 0;
+}
+
 function methodGuard(allowed) {
   return (req, res, next) => {
     if (!allowed.includes(req.method)) {
diff --git a/backend/server.js b/backend/server.js
index 04591e4..710e2a6 100644
--- a/backend/server.js
+++ b/backend/server.js
@@ -69,6 +69,12 @@ app.use(express.urlencoded({ extended: true, limit: '1mb' }));
 app.use(sanitizeBody);
 app.use(generalLimiter);
 app.use('/api', apiKeyGuard);
+app.use('/api', (req, res, next) => {
+  res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate, private');
+  res.setHeader('Pragma', 'no-cache');
+  res.setHeader('Referrer-Policy', 'strict-origin-when-cross-origin');
+  next();
+});
 
 const staticOpts = {
   maxAge: 0,
diff --git a/backend/webhook.js b/backend/webhook.js
index eb98811..5156a6a 100644
--- a/backend/webhook.js
+++ b/backend/webhook.js
@@ -2,12 +2,29 @@ const { query, getRow } = require('./db');
 
 const EVENT_LABELS = { ticket_created:'工单创建', ticket_claimed:'工单认领', ticket_transferred:'工单转交', ticket_updated:'工单更新' };
 
+const dns = require('dns').promises;
+const { URL } = require('url');
+
+async function isPrivateUrl(urlStr) {
+  try {
+    const u = new URL(urlStr);
+    if (u.hostname === 'localhost' || u.hostname === '127.0.0.1' || u.hostname === '0.0.0.0') return true;
+    if (u.hostname.startsWith('192.168.') || u.hostname.startsWith('10.') || u.hostname.startsWith('172.16.')) return true;
+    const addrs = await dns.resolve4(u.hostname).catch(() => []);
+    for (const addr of addrs) {
+      if (addr === '127.0.0.1' || addr.startsWith('192.168.') || addr.startsWith('10.') || addr.startsWith('172.16.') || addr.startsWith('0.')) return true;
+    }
+    return false;
+  } catch { return true; }
+}
+
 async function sendWebhook(event, data) {
   try {
     const configs = await query("SELECT * FROM notification_configs WHERE type = 'webhook' AND active = 1");
     for (const cfg of configs) {
       const events = cfg.events || 'all';
       if (events !== 'all' && !events.split(',').map(s=>s.trim()).includes(event)) continue;
+      if (cfg.webhook_url && await isPrivateUrl(cfg.webhook_url)) { console.error('[Webhook] blocked internal URL:', cfg.name); continue; }
       const embed = buildEmbed(event, data);
       try {
         const ctrl = new AbortController();