diff --git a/backend/mailer.js b/backend/mailer.js
index de2f35e..eb14fcf 100644
--- a/backend/mailer.js
+++ b/backend/mailer.js
@@ -42,17 +42,28 @@ function renderTemplate(template, vars) {
   return { subject, body };
 }
 
+let _transporter = null;
+let _transporterKey = '';
+
+function getTransporter(cfg) {
+  const key = `${cfg.host}:${cfg.port}:${cfg.user}`;
+  if (_transporter && _transporterKey === key) return _transporter;
+  _transporterKey = key;
+  _transporter = nodemailer.createTransport({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: { user: cfg.user, pass: cfg.pass } });
+  return _transporter;
+}
+
 async function sendEmail(to, templateCode, vars) {
   try {
     const cfg = await getSmtpConfig();
     if (!cfg.host || !cfg.user) { console.log('[Mailer] SMTP未配置'); return false; }
     const template = await getTemplate(templateCode);
     if (!template) { console.log('[Mailer] 模板不存在:', templateCode); return false; }
-    const allVars = { ...vars, site_name: await getSiteName(), site_url: await getSiteUrl() };
+    const siteName = await getSiteName();
+    const allVars = { ...vars, site_name: siteName, site_url: await getSiteUrl() };
     const { subject, body } = renderTemplate(template, allVars);
-
-    const transporter = nodemailer.createTransport({ host: cfg.host, port: cfg.port, secure: cfg.secure, auth: { user: cfg.user, pass: cfg.pass } });
-    await transporter.sendMail({ from: `"${await getSiteName()}" <${cfg.from}>`, to, subject, html: body });
+    const transporter = getTransporter(cfg);
+    await transporter.sendMail({ from: `"${siteName}" <${cfg.from}>`, to, subject, html: body });
     return true;
   } catch (err) { console.error('[Mailer]', err.message); return false; }
 }
diff --git a/backend/middleware/auth.js b/backend/middleware/auth.js
index afad4b9..0d5c9c7 100644
--- a/backend/middleware/auth.js
+++ b/backend/middleware/auth.js
@@ -4,8 +4,13 @@ const { getConfig } = require('../db');
 function getSecret() {
   try {
     const cfg = getConfig();
-    return cfg?.jwt_secret || process.env.JWT_SECRET || 'mc-dev-secret';
-  } catch { return process.env.JWT_SECRET || 'mc-dev-secret'; }
+    const secret = cfg?.jwt_secret || process.env.JWT_SECRET;
+    if (secret) return secret;
+    throw new Error('JWT_SECRET not configured');
+  } catch (e) {
+    if (e.message === 'JWT_SECRET not configured') throw e;
+    return process.env.JWT_SECRET || (() => { throw new Error('JWT_SECRET not configured'); })();
+  }
 }
 
 function generateToken(user) {
diff --git a/backend/middleware/security.js b/backend/middleware/security.js
index 2fcbef2..5266d1f 100644
--- a/backend/middleware/security.js
+++ b/backend/middleware/security.js
@@ -33,13 +33,14 @@ function sanitize(value) {
 }
 
 function sanitizeBody(req, res, next) {
-  if (req.body) {
-    for (const key of Object.keys(req.body)) {
-      if (typeof req.body[key] === 'string') {
-        req.body[key] = sanitize(req.body[key]);
-      }
+  function walk(obj) {
+    if (!obj || typeof obj !== 'object') return;
+    for (const key of Object.keys(obj)) {
+      if (typeof obj[key] === 'string') obj[key] = sanitize(obj[key]);
+      else if (typeof obj[key] === 'object') walk(obj[key]);
     }
   }
+  walk(req.body);
   next();
 }
 
diff --git a/backend/middleware/upload.js b/backend/middleware/upload.js
index 10ba05e..d81ea51 100644
--- a/backend/middleware/upload.js
+++ b/backend/middleware/upload.js
@@ -24,7 +24,7 @@ function validateMagicBytes(buffer, mime) {
     'image/png': () => head[0] === 0x89 && head[1] === 0x50 && head[2] === 0x4E && head[3] === 0x47,
     'image/gif': () => head.toString('ascii', 0, 6) === 'GIF89a' || head.toString('ascii', 0, 6) === 'GIF87a',
     'image/webp': () => head.toString('ascii', 0, 4) === 'RIFF' && head.toString('ascii', 8, 12) === 'WEBP',
-    'video/mp4': () => buffer.includes(Buffer.from('ftyp')),
+    'video/mp4': () => buf[4] === 0x66 && buf[5] === 0x74 && buf[6] === 0x79 && buf[7] === 0x70,
     'video/webm': () => head[0] === 0x1A && head[1] === 0x45 && head[2] === 0xDF && head[3] === 0xA3,
   };
   if (!sigs[mime]) return false;
@@ -58,18 +58,22 @@ const upload = multer({
 
 function finalizeUpload(req, res, next) {
   if (!req.files || req.files.length === 0) return next();
-  for (const file of req.files) {
-    const buf = fs.readFileSync(file.path);
-    if (!ALLOWED_MIME[file.mimetype]) {
-      fs.unlinkSync(file.path);
-      return res.status(400).json({ error: `不支持的文件类型: ${file.mimetype}` });
-    }
-    if (!validateMagicBytes(buf, file.mimetype)) {
-      fs.unlinkSync(file.path);
-      return res.status(400).json({ error: '文件内容与声明类型不符，可能是恶意文件' });
+  const filePaths = [];
+  try {
+    for (const file of req.files) {
+      const fd = fs.openSync(file.path, 'r');
+      const buf = Buffer.alloc(256);
+      fs.readSync(fd, buf, 0, 256, 0);
+      fs.closeSync(fd);
+      filePaths.push(file.path);
+      if (!ALLOWED_MIME[file.mimetype]) throw new Error(`不支持的文件类型: ${file.mimetype}`);
+      if (!validateMagicBytes(buf, file.mimetype)) throw new Error('文件内容与声明类型不符，可能是恶意文件');
     }
+    next();
+  } catch (e) {
+    for (const fp of filePaths) { try { fs.unlinkSync(fp); } catch {} }
+    return res.status(400).json({ error: e.message || '文件校验失败' });
   }
-  next();
 }
 
 module.exports = { upload, finalizeUpload, validateMagicBytes, UPLOAD_DIR, ALLOWED_MIME };
diff --git a/backend/routes/external.js b/backend/routes/external.js
index e82bf73..936bf9c 100644
--- a/backend/routes/external.js
+++ b/backend/routes/external.js
@@ -1,7 +1,7 @@
 const express = require('express');
 const bcrypt = require('bcryptjs');
 const { v4: uuid } = require('uuid');
-const { query, getRow, getConfig } = require('../db');
+const { query, getRow, getConfig, getPool } = require('../db');
 const { generateToken, authenticate } = require('../middleware/auth');
 const { sendEmail } = require('../mailer');
 
@@ -47,7 +47,7 @@ router.post('/auth/login', async (req, res) => {
     const { username, password } = req.body;
     if (!username || !password) return res.status(400).json({ error: '请输入用户名和密码' });
     const user = await getRow('SELECT * FROM users WHERE username = ?', [username]);
-    if (!user || !bcrypt.compareSync(password, user.password)) return res.status(401).json({ error: '用户名或密码错误' });
+    if (!user || !(await bcrypt.compare(password, user.password))) return res.status(401).json({ error: '用户名或密码错误' });
     if (!user.active) return res.status(403).json({ error: '账号未激活' });
     const token = generateToken(user);
     res.json({ token, user: { id:user.id, username:user.username, game_name:user.game_name, game_uid:user.game_uid, role:user.role } });
diff --git a/backend/routes/tickets.js b/backend/routes/tickets.js
index ea46e10..7ed3aae 100644
--- a/backend/routes/tickets.js
+++ b/backend/routes/tickets.js
@@ -185,6 +185,7 @@ router.put('/:id', authenticate, requireRole('owner','admin'), async (req, res)
   const fields = {};
   if (req.body.status) fields.status = req.body.status;
   if (req.body.priority) fields.priority = req.body.priority;
+  if (req.body.priority && !['low','medium','high','urgent'].includes(req.body.priority)) return res.status(400).json({ error: '无效的优先级' });
   if (req.body.claim_note !== undefined) fields.claim_note = req.body.claim_note;
   if (!Object.keys(fields).length) return res.status(400).json({ error: '无更新内容' });
   const sets = Object.keys(fields).map(k => `${k} = ?`).join(', ');
diff --git a/backend/server.js b/backend/server.js
index 3bdacd3..04591e4 100644
--- a/backend/server.js
+++ b/backend/server.js
@@ -125,7 +125,7 @@ app.use((err, req, res, next) => {
   res.status(500).json({ error: '服务器内部错误' });
 });
 
-if (isInstalled()) console.log(`Server running at http://localhost:${PORT}`);
-else console.log(`System not installed. Visit http://localhost:${PORT}/#/install`);
-
-app.listen(PORT);
+app.listen(PORT, () => {
+  if (isInstalled()) console.log(`Server running at http://localhost:${PORT}`);
+  else console.log(`System not installed. Visit http://localhost:${PORT}/#/install`);
+}).on('error', (err) => { console.error('Failed to start:', err.message); process.exit(1); });
diff --git a/backend/webhook.js b/backend/webhook.js
index e4db5f9..eb98811 100644
--- a/backend/webhook.js
+++ b/backend/webhook.js
@@ -9,7 +9,12 @@ async function sendWebhook(event, data) {
       const events = cfg.events || 'all';
       if (events !== 'all' && !events.split(',').map(s=>s.trim()).includes(event)) continue;
       const embed = buildEmbed(event, data);
-      try { await fetch(cfg.webhook_url, { method:'POST', headers:{'Content-Type':'application/json'}, body:JSON.stringify(embed) }); } catch {}
+      try {
+        const ctrl = new AbortController();
+        const t = setTimeout(() => ctrl.abort(), 10000);
+        await fetch(cfg.webhook_url, { method:'POST', headers:{'Content-Type':'application/json'}, body:JSON.stringify(embed), signal: ctrl.signal });
+        clearTimeout(t);
+      } catch (e) { console.error('[Webhook]', cfg.name, e.message); }
     }
   } catch {}
 }