CVE-2026-89063 describes an Insecure Direct Object Reference vulnerability in the Bookly WordPress plugin (versions up to 28.1). The 'conversation_id' parameter is user-controlled and lacks proper validation, enabling unauthenticated attackers to enumerate and access all AI booking conversation transcripts. This leads to unauthorized disclosure of personal information and allows injection of arbitrary messages into conversations. The root cause is missing authorization checks combined with sequential conversation IDs and absence of ownership metadata in stored conversations.

An unauthenticated attacker can read private AI booking conversation transcripts containing sensitive customer information such as names, email addresses, phone numbers, and appointment details. The attacker can also inject arbitrary messages into any victim conversation, potentially influencing the AI assistant's behavior. This results in a high confidentiality impact but does not affect integrity or availability according to the CVSS vector.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict access to the plugin and monitor for suspicious activity. Avoid exposing the 'conversation_id' parameter to unauthenticated users. Implement additional access controls or disable the affected feature if possible.