CVE-2026-118691

xianyu-auto-reply-fix through 2.0.7 contains a missing authorization vulnerability in the POST /send-message endpoint that allows unauthenticated attackers to send messages from other users' accounts using publicly known default API secrets. Attackers can supply the hard-coded api key and another user's cookie id, plus chosen chat id, to user id and message values, to send arbitrary Xianyu messages to buyers from that merchant account.