A security flaw exists in youlaitech youlai-mall. The issue involves improper authorization within the Balance Handler component. Specifically, the `deductBalance` function, located in the file mall-ums/ums-boot/src/main/java/com/youlai/mall/ums/controller/app/MemberController.java, is susceptible to manipulation. This allows for remote attacks. The exploit for this issue is publicly available. The vendor was notified but did not respond.