Description

The Booking for Appointments and Events Calendar WordPress plugin before 2.4.9 does not require authentication or a valid request token before running the post-booking action chain, allowing an unauthenticated user to trigger booking notifications and integration callbacks for a booking by enumerating its identifier.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-09-02T06:17:16.010Z",
  "pubdate": "2026-09-02T06:17:16.010Z",
  "executiveSummary": "The Booking for Appointments and Events Calendar WordPress plugin prior to version 2.4.9 contains a critical vulnerability related to improper authorization controls. Specifically, the plugin fails to enforce authentication or validate request tokens during the execution of its post-booking action chain.\nThis architectural flaw allows unauthenticated remote attackers to trigger sensitive booking notifications and integration callbacks by submitting malicious requests containing enumerated booking identifiers. The vulnerability essentially exposes internal post-processing workflows to the public internet.\nThe primary risk implications include unauthorized disclosure of booking information, potential manipulation of third-party integration states, and the possibility of resource exhaustion or notification spamming. An attacker does not require any specialized privileges or prior system access, as the vulnerability is exploitable via simple HTTP requests. By systematically cycling through sequential or predictable booking IDs, an adversary can remotely execute server-side logic intended only for authenticated administrative users or legitimate booking events.\nOrganizations relying on this plugin are at risk of data leakage and workflow interference. Immediate remediation through patching is required to restore secure authorization protocols.",
  "technicalDetails": "The root cause of this vulnerability lies in the plugin's failure to implement identity verification or non-repudiation mechanisms within the post-booking action handler. In standard WordPress development, sensitive actions that trigger notifications (e.g., email dispatch, webhooks to third-party services) must be guarded by checks such as current_user_can() or the validation of a nonce (number used once). In this instance, the plugin handles these requests in a globally accessible scope, lacking any verification of the requester's context.\nExploitation is achieved through an insecure direct object reference (IDOR) pattern coupled with an authentication bypass. Because the plugin does not validate a request token, the backend handler processes input parameters identifying a specific booking without confirming that the user has the authority to view or trigger events for that booking. An attacker can perform reconnaissance by identifying the URL structure of the booking endpoint and then crafting a request that includes a specific 'booking_id' parameter.\nThe attack flow follows a predictable sequence: First, the attacker identifies a valid target endpoint within the plugin that initiates the post-booking action chain. Second, the attacker performs automated enumeration of the numeric or alphanumeric booking identifiers. Third, the attacker sends specially crafted HTTP POST or GET requests to the identified endpoint, injecting the guessed or discovered booking ID. The vulnerable component, upon receiving this input, fails to perform a check against the session or user capability, and immediately proceeds to execute the associated logic.\nThe resulting impact is significant: the system blindly executes integration callbacks, which may trigger outbound webhooks or email alerts. This allows an attacker to effectively 'spoof' booking confirmations or cancellations. Furthermore, because these actions are automated, an attacker can launch a denial-of-service (DoS) condition by forcing the plugin to repeatedly trigger external API calls or email queues, potentially leading to service degradation or blacklisting of the WordPress server’s IP address by third-party mail relay services due to excessive, non-legitimate traffic.\nThe vulnerability affects all versions of the Booking for Appointments and Events Calendar plugin before 2.4.9. The lack of network segmentation or firewall rules protecting the WordPress admin area does not mitigate this, as the vulnerable code paths are typically exposed via front-end hooks or public-facing API endpoints."
}