CVE-2026-84764 in Simply Schedule Appointments Plugin
Summary
by MITRE • 09/02/2026
Unauthenticated Cross Site Request Forgery (CSRF) in Simply Schedule Appointments <= 1.6.12.23 versions.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified as an unauthenticated Cross-Site Request Forgery within the Simply Schedule Appointment plugin for WordPress, affecting versions up to and including 1.6.12.23, represents a critical security flaw that undermines the integrity of administrative actions through deceptive user interactions. This type of attack exploits the inherent trust that web applications place in users' browsers, allowing an attacker to trick authenticated administrators into performing unintended functions without their knowledge or consent. The core technical issue stems from the application's failure to implement adequate anti-CSRF mechanisms, such as unique and unpredictable tokens for state-changing requests, which are essential for verifying that a request originates from a legitimate user session rather than a malicious third-party site.
From a technical perspective, the flaw allows an attacker to craft a malicious webpage or email containing hidden form submissions or image tags with specific URLs targeting vulnerable endpoints within the plugin's administration interface. When an administrator visits this crafted page while logged into their WordPress dashboard, the browser automatically includes session cookies and authentication credentials in the request headers due to same-origin policy exceptions for certain resource types like images or scripts if not properly configured. Consequently, the server processes these requests as valid administrative actions because it cannot distinguish them from legitimate user-initiated operations. This lack of verification enables the execution of privileged commands such as modifying appointment settings, creating new admin users, or altering plugin configurations without any direct interaction required from the victim beyond visiting a malicious link.
The operational impact of this vulnerability is severe given the high-privilege nature of WordPress administrators who typically have full control over site content and configuration. An attacker leveraging this CSRF flaw can escalate privileges by adding a new administrator account with their own credentials, thereby gaining persistent access to the compromised system even if the original admin password is changed later. Furthermore, the ability to manipulate appointment scheduling data could lead to business disruption for organizations relying on the plugin for client bookings or service management. In more advanced attack scenarios, this vulnerability can serve as a stepping stone for further exploitation, such as injecting malicious scripts into scheduled appointments that execute when viewed by clients, leading to broader cross-site scripting attacks against end-users and potential data exfiltration from sensitive appointment records containing personal information.
This weakness aligns with CWE-352, which defines Cross-Site Request Forgery as a vulnerability where a web application executes unwanted commands on behalf of an authenticated user without their consent. It also maps to the MITRE ATT&CK framework under T1078, specifically relating to Valid Accounts and potentially T1190 for Exploit Public-Facing Application if leveraged in conjunction with other initial access vectors. The absence of anti-forgery tokens is a common oversight in older plugin versions that may not have been updated to meet modern security standards requiring robust state-change protection mechanisms across all administrative endpoints.
Mitigation strategies must prioritize immediate patching by upgrading the Simply Schedule Appointment plugin to version 1.6.12.24 or later, where these CSRF protections are likely implemented through nonce verification and strict origin checking on sensitive API calls. Until an update is applied, administrators should consider disabling public access to affected endpoints if possible or implementing web application firewall rules that detect and block suspicious request patterns indicative of CSRF attempts. Additionally, enforcing strong session management policies such as shorter cookie lifetimes and requiring re-authentication for critical administrative actions can reduce the window of opportunity for attackers exploiting this vulnerability. Regular security audits and adherence to secure coding practices including mandatory token validation for all state-changing operations are essential preventive measures against similar vulnerabilities in future development cycles.