CVE-2026-86729WWBN AVideo through commit e01e41ecc (no patched version available) exposes get_api_preauthorize in plugin/API/API.php as a second, undocumented login path. Unlike get_api_signIn, which enforces a rate limit of 10 attempts per 5 minutes via checkRateLimit(), get_api_preauthorize performs the same credential check with no throttling for any client, allowing unlimited remote password guessing against arbitrary accounts, including admin. The endpoint also acts as a credential oracle: it returns the message "Invalid credentials" for both correct and incorrect passwords, while the users_id field in the response body discloses the authenticated identity (users_id:1 on success, users_id:0 on failure), and a correct password establishes a session cookie that remains usable for authenticated API requests. Together these issues permit unauthenticated brute-force account takeover.