diff --git a/app.py b/app.py
index 77c771d..7b0349e 100755
--- a/app.py
+++ b/app.py
@@ -98,11 +98,17 @@ user_accounts = {}  # {user_id: {account_id: Account对象}}
 active_tasks = {}  # {account_id: Thread对象}
 task_status = {}  # {account_id: {"user_id": x, "username": y, "status": "排队中/运行中", "detail_status": "具体状态", "browse_type": z, "start_time": t, "source": s, "progress": {...}, "is_vip": bool}}
 
+# 线程安全锁 - 修复Bug #12
+active_tasks_lock = threading.Lock()  # 保护 active_tasks 字典
+task_status_lock = threading.Lock()   # 保护 task_status 字典
+user_accounts_lock = threading.Lock() # 保护 user_accounts 字典
+
 # VIP优先级队列
 vip_task_queue = []  # VIP用户任务队列
 normal_task_queue = []  # 普通用户任务队列
 task_queue_lock = threading.Lock()
 log_cache = {}  # {user_id: [logs]} 每个用户独立的日志缓存
+log_cache_lock = threading.Lock()  # 保护 log_cache 字典
 log_cache_total_count = 0  # 全局日志总数,防止无限增长
 
 # 日志缓存限制
@@ -214,6 +220,73 @@ class Account:
         return result
 
 
+# ========== 线程安全辅助函数 - 修复Bug #12 ==========
+
+def safe_set_task(account_id, thread):
+    """线程安全地设置任务"""
+    with active_tasks_lock:
+        active_tasks[account_id] = thread
+
+def safe_get_task(account_id):
+    """线程安全地获取任务"""
+    with active_tasks_lock:
+        return active_tasks.get(account_id)
+
+def safe_remove_task(account_id):
+    """线程安全地移除任务"""
+    with active_tasks_lock:
+        return active_tasks.pop(account_id, None)
+
+def safe_set_task_status(account_id, status_dict):
+    """线程安全地设置任务状态"""
+    with task_status_lock:
+        task_status[account_id] = status_dict
+
+def safe_update_task_status(account_id, updates):
+    """线程安全地更新任务状态"""
+    with task_status_lock:
+        if account_id in task_status:
+            task_status[account_id].update(updates)
+
+def safe_get_task_status(account_id):
+    """线程安全地获取任务状态"""
+    with task_status_lock:
+        return task_status.get(account_id, {}).copy()
+
+def safe_remove_task_status(account_id):
+    """线程安全地移除任务状态"""
+    with task_status_lock:
+        return task_status.pop(account_id, None)
+
+def safe_get_all_task_status():
+    """线程安全地获取所有任务状态"""
+    with task_status_lock:
+        return {k: v.copy() for k, v in task_status.items()}
+
+def safe_add_log(user_id, log_entry):
+    """线程安全地添加日志"""
+    global log_cache_total_count
+    with log_cache_lock:
+        if user_id not in log_cache:
+            log_cache[user_id] = []
+
+        # 限制每个用户的日志数量
+        if len(log_cache[user_id]) >= MAX_LOGS_PER_USER:
+            log_cache[user_id].pop(0)
+            log_cache_total_count = max(0, log_cache_total_count - 1)
+
+        log_cache[user_id].append(log_entry)
+        log_cache_total_count += 1
+
+        # 全局日志总数限制
+        if log_cache_total_count > MAX_TOTAL_LOGS:
+            # 删除最早用户的最早日志
+            for uid in list(log_cache.keys()):
+                if log_cache[uid]:
+                    log_cache[uid].pop(0)
+                    log_cache_total_count -= 1
+                    break
+
 @login_manager.user_loader
 def load_user(user_id):
     """Flask-Login 用户加载"""
@@ -2078,6 +2151,10 @@ def serve_screenshot(filename):
     if not filename.startswith(username_prefix + '_'):
         return jsonify({"error": "无权访问"}), 403
 
+    # 防止路径遍历攻击 (Bug #19 fix)
+    if not is_safe_path(SCREENSHOTS_DIR, filename):
+        return jsonify({"error": "非法路径"}), 403
+
     return send_from_directory(SCREENSHOTS_DIR, filename)
 
 
@@ -2177,6 +2254,10 @@ def handle_disconnect():
 @app.route('/static/<path:filename>')
 def serve_static(filename):
     """提供静态文件访问"""
+    # 防止路径遍历攻击 (Bug #19 fix)
+    if not is_safe_path('static', filename):
+        return jsonify({"error": "非法路径"}), 403
+
     response = send_from_directory('static', filename)
     # 禁用缓存，强制浏览器每次都重新加载
     response.headers['Cache-Control'] = 'no-store, no-cache, must-revalidate, max-age=0'
diff --git a/playwright_automation.py b/playwright_automation.py
index 8b9af25..6393855 100755
--- a/playwright_automation.py
+++ b/playwright_automation.py
@@ -149,6 +149,7 @@ class PlaywrightAutomation:
         self.page: Optional[Page] = None
         self.main_page: Optional[Page] = None
         self._closed = False  # 防止重复关闭
+        self._lock = threading.Lock()  # Bug #13 fix: 保护浏览器资源访问
 
         # 注册退出清理函数，确保进程异常退出时也能关闭浏览器
         atexit.register(self._cleanup_on_exit)
@@ -434,14 +435,16 @@ class PlaywrightAutomation:
         """
         for attempt in range(max_retries if retry else 1):
             try:
-                # 先检查main_page是否有效
-                if not self.main_page:
-                    self.log("⚠ main_page无效")
-                    return None
+                # Bug #13 fix: 使用锁保护main_page访问
+                with self._lock:
+                    # 先检查main_page是否有效
+                    if not self.main_page:
+                        self.log("⚠ main_page无效")
+                        return None
 
-                iframe = self.main_page.frame('mainframe')
-                if iframe:
-                    return iframe
+                    iframe = self.main_page.frame('mainframe')
+                    if iframe:
+                        return iframe
             except Exception as e:
                 error_msg = str(e)
                 if self.is_context_error(error_msg):
@@ -1327,49 +1330,51 @@ class PlaywrightAutomation:
 
     def close(self):
         """完全关闭浏览器进程(每个账号独立)并确保资源释放"""
-        # 防止重复关闭
-        if self._closed:
-            return
-        self._closed = True
+        # Bug #13 fix: 使用锁保护close操作
+        with self._lock:
+            # 防止重复关闭
+            if self._closed:
+                return
+            self._closed = True
 
-        errors = []
+            errors = []
 
-        # 第一步:关闭上下文
-        if self.context:
-            try:
-                self.context.close()
-                # self.log("上下文已关闭")  # 精简日志
-            except Exception as e:
-                error_msg = f"关闭上下文时出错: {str(e)}"
-                self.log(error_msg)
-                errors.append(error_msg)
+            # 第一步:关闭上下文
+            if self.context:
+                try:
+                    self.context.close()
+                    # self.log("上下文已关闭")  # 精简日志
+                except Exception as e:
+                    error_msg = f"关闭上下文时出错: {str(e)}"
+                    self.log(error_msg)
+                    errors.append(error_msg)
 
-        # 第二步:关闭浏览器进程
-        if self.browser:
-            try:
-                self.browser.close()
-                # self.log("浏览器进程已关闭")  # 精简日志
-            except Exception as e:
-                error_msg = f"关闭浏览器时出错: {str(e)}"
-                self.log(error_msg)
-                errors.append(error_msg)
+            # 第二步:关闭浏览器进程
+            if self.browser:
+                try:
+                    self.browser.close()
+                    # self.log("浏览器进程已关闭")  # 精简日志
+                except Exception as e:
+                    error_msg = f"关闭浏览器时出错: {str(e)}"
+                    self.log(error_msg)
+                    errors.append(error_msg)
 
-        # 第三步:停止Playwright
-        if self.playwright:
-            try:
-                self.playwright.stop()
-                # self.log("Playwright已停止")  # 精简日志
-            except Exception as e:
-                error_msg = f"停止Playwright时出错: {str(e)}"
-                self.log(error_msg)
-                errors.append(error_msg)
+            # 第三步:停止Playwright
+            if self.playwright:
+                try:
+                    self.playwright.stop()
+                    # self.log("Playwright已停止")  # 精简日志
+                except Exception as e:
+                    error_msg = f"停止Playwright时出错: {str(e)}"
+                    self.log(error_msg)
+                    errors.append(error_msg)
 
-        # 第四步:清空引用,确保垃圾回收
-        self.context = None
-        self.page = None
-        self.main_page = None
-        self.browser = None
-        self.playwright = None
+            # 第四步:清空引用,确保垃圾回收
+            self.context = None
+            self.page = None
+            self.main_page = None
+            self.browser = None
+            self.playwright = None
 
         # 第五步:强制等待,确保进程完全退出
         time.sleep(0.5)
@@ -1383,18 +1388,24 @@ class PlaywrightAutomation:
 
     def _cleanup_on_exit(self):
         """进程退出时的清理函数（由atexit调用）"""
-        if not self._closed:
-            try:
-                # 静默关闭，避免在退出时产生过多日志
-                if self.context:
-                    self.context.close()
-                if self.browser:
-                    self.browser.close()
-                if self.playwright:
-                    self.playwright.stop()
-                self._closed = True
-            except:
-                pass  # 退出时忽略所有错误
+        # Bug #13 fix: 尝试获取锁，但不阻塞（避免退出时死锁）
+        acquired = self._lock.acquire(blocking=False)
+        try:
+            if not self._closed:
+                try:
+                    # 静默关闭，避免在退出时产生过多日志
+                    if self.context:
+                        self.context.close()
+                    if self.browser:
+                        self.browser.close()
+                    if self.playwright:
+                        self.playwright.stop()
+                    self._closed = True
+                except:
+                    pass  # 退出时忽略所有错误
+        finally:
+            if acquired:
+                self._lock.release()
 
     def __enter__(self):
         """Context manager支持 - 进入"""