CVE-2026-89063: Online Scheduling and Appointment Booking System <= 28.1 - Insecure Direct Object Reference to Unauthenticated Sensitive Data Access and Message Injection via 'conversation_id' Parameter

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-09-16 · updated 2026-09-17
Weakness: CWE-639

Description

The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 28.1 via the 'conversation_id' parameter due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to read the full AI booking conversation transcript of any customer — leaking names, email addresses, phone numbers, and appointment details echoed by the assistant — and inject arbitrary messages into any victim conversation that are subsequently replayed to the Cloud AI worker along with the full private history. Because AI conversations are stored with no owner, user, or session identifier and conversation IDs are sequential integers, an unauthenticated attacker can enumerate all customer conversations simply by incrementing the conversation_id parameter.

Affected products

ladela Online Scheduling and Appointment Booking System – Bookly: through 28.1

References

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