CVE-2026-94673 in Simply Schedule Appointments Plugin
Summary
by MITRE • 09/30/2026
Unauthenticated Insecure Direct Object References (IDOR) in Simply Schedule Appointments <= 1.6.12.31 versions.
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Analysis
by VulDB Data Team • 09/30/2026
The vulnerability identified as an Unauthenticated Insecure Direct Object Reference within the Simply Schedule Appointment plugin for WordPress, affecting versions up to and including 1.6.12.31, represents a critical failure in access control mechanisms that allows attackers to manipulate object identifiers directly without proper authorization checks. This flaw stems from the application's reliance on client-supplied input parameters to determine which database records or resources should be accessed, coupled with an absence of server-side validation to ensure that the requesting user has legitimate permissions for those specific objects. In a secure implementation, every request to access sensitive data must verify not only the identity of the requester but also their authorization level relative to the target resource. However, in this vulnerable configuration, the application fails to enforce these checks before processing requests aimed at retrieving or modifying appointment details, client information, or administrative settings stored within the WordPress database structure.
From a technical perspective, this vulnerability aligns closely with CWE-639, which describes Insecure Direct Object References where an application exposes internal implementation objects such as files, directories, or database keys to end users without adequate access control checks. The exploitation of this flaw typically involves intercepting HTTP requests using tools like Burp Suite and modifying parameters that identify specific records, such as appointment IDs or user identifiers. Because the vulnerability is unauthenticated, attackers do not need valid credentials to initiate these attacks, significantly lowering the barrier for entry. This characteristic places the vulnerability within the MITRE ATT&CK framework under techniques related to Collection via Client Side Payloads or potentially T1078 Valid Accounts if combined with other vectors, though in this specific context, it primarily facilitates unauthorized data access through direct manipulation of resource identifiers without prior authentication requirements.
The operational impact of this vulnerability is severe, as it can lead to the complete compromise of sensitive business and personal information managed by the scheduling application. Attackers can potentially view private appointment schedules, client contact details including names, phone numbers, email addresses, and medical or service history if such data is stored in accessible fields. Furthermore, depending on how the underlying functions handle input after retrieval, there may be secondary risks involving modification of records, leading to integrity violations where malicious actors could alter appointment times, cancel bookings without authorization, or inject fraudulent entries into the system. For businesses relying on this plugin for customer relationship management and operational logistics, such unauthorized access undermines trust and can result in significant financial loss due to disrupted services or regulatory penalties associated with data breaches involving personally identifiable information.
Mitigation strategies must prioritize immediate remediation through software updates as well as defensive coding practices if updating is not immediately feasible. The primary recommendation is to upgrade the Simply Schedule Appointment plugin to a version newer than 1.6.12.31, where developers have presumably implemented proper authorization checks and input validation mechanisms. For environments unable to update immediately due to compatibility constraints or other operational dependencies, temporary mitigations should include restricting access to WordPress admin endpoints via IP whitelisting if the vulnerability is triggered through administrative interfaces, although this may not fully protect against all attack vectors given the unauthenticated nature of the flaw. Additionally, implementing Web Application Firewall rules that detect and block anomalous patterns in parameter manipulation can provide a layer of defense by identifying requests with suspiciously sequential or manipulated object IDs. Long-term architectural improvements should involve adopting principle of least privilege for database queries and ensuring that all API endpoints enforce strict authentication and authorization protocols before processing any data retrieval or modification operations, thereby eliminating the possibility of direct object reference exploitation entirely.