WordPressプラグイン「Better Messages – Chat Rooms, Group Chat, Private Messages & AI Chat Bots」に不適切な認証の脆弱性（CVE-2026-89093）

The Better Messages – Chat Rooms, Group Chat, Private Messages & AI Chat Bots plugin for WordPress is vulnerable to Information Exposure by Spoofing in all versions up to, and including, 2.15.33. This is due to the `is_ai_bot_user()` function identifying privileged internal AI bot accounts by performing a prefix check for `'ai-chat-bot-'` against a guest record's stored IP address, which is populated verbatim from the client-controlled `X-Real-IP` request header during unauthenticated guest registration. This makes it possible for unauthenticated attackers to register a guest identity that the plugin treats as its own internal AI bot, bypassing the per-room role allowlist, draft-status check, and join filters — which are all short-circuited by the bot check in `user_can_join()` and `user_can_read()` — to join administrator-restricted chat rooms, post messages into them, and read the private message history of other users.