CVE-2026-12378 in Appointment Booking Calendar Plugin and Scheduling Plugin Plugin
Summary
by MITRE • 07/08/2026
The Appointment Booking Calendar Plugin and Scheduling Plugin WordPress plugin through 1.1.28 does not validate data before passing it to a PHP deserialization function, allowing unauthenticated attackers to inject arbitrary PHP objects; where a suitable gadget chain is present on the site this can be leveraged to achieve remote code execution.
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Analysis
by VulDB Data Team • 07/08/2026
The vulnerability in question affects the Appointment Booking Calendar Plugin and Scheduling Plugin WordPress plugin versions up to 1.1.28, representing a critical security flaw that stems from insufficient input validation mechanisms within the plugin's core functionality. This weakness creates an attack surface where unauthenticated threat actors can exploit the lack of proper sanitization before data is processed through PHP's deserialization functions. The issue directly relates to CWE-502 which categorizes insecure deserialization as a serious vulnerability pattern that can lead to arbitrary code execution when malicious objects are introduced into the deserialization process.
The technical implementation flaw occurs when user-supplied data is passed directly to PHP's unserialize() function without adequate validation or sanitization measures. When an attacker crafts malicious input containing serialized PHP objects, and if the target website contains suitable gadget chains within its autoloaded libraries or classes, the system will attempt to deserialize these objects automatically. This automatic deserialization process can trigger method calls on the contained objects, potentially leading to remote code execution through exploitation of the gadget chain. The vulnerability is particularly dangerous because it does not require authentication credentials to exploit, making it accessible to any attacker with knowledge of the target site's structure.
The operational impact of this vulnerability extends beyond simple code execution capabilities, as it can enable attackers to gain complete control over compromised WordPress installations and potentially escalate privileges within broader network environments. The attack surface is particularly concerning given that many WordPress sites may contain vulnerable libraries or frameworks that provide suitable gadget chains for exploitation, especially in environments where multiple plugins or themes are installed. This vulnerability creates opportunities for attackers to establish persistent backdoors, exfiltrate sensitive data, modify website content, or use the compromised system as a launchpad for further attacks against other systems within the network infrastructure.
Mitigation strategies should prioritize immediate plugin updates to versions that address the deserialization vulnerability through proper input validation and sanitization measures. Security teams must implement comprehensive monitoring of deserialization activities within their WordPress environments and establish strict validation protocols for all user inputs that may be processed by PHP functions. The principle of least privilege should be enforced by ensuring that web server processes run with minimal required permissions, while also implementing proper network segmentation to limit lateral movement if compromise occurs. Additionally, organizations should conduct thorough security assessments of their WordPress installations to identify and remediate similar vulnerabilities in other plugins or themes, as this type of vulnerability often indicates broader insecure coding practices within the application ecosystem. The ATT&CK framework's T1059.007 technique for command and scripting interpreter - php specifically applies to this scenario, highlighting how attackers can leverage PHP deserialization vulnerabilities to execute arbitrary code on target systems.