CVE-2026-95606 in The Events Calendar Plugin
Summary
by MITRE • 10/07/2026
Deserialization of Untrusted Data vulnerability in Liquid Web / StellarWP The Events Calendar allows Object Injection.
This issue affects The Events Calendar: from n/a through 6.17.4.
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Analysis
by VulDB Data Team • 10/07/2026
The discovery of a deserialization of untrusted data vulnerability within the popular WordPress plugin, The Events Calendar by StellarWP and Liquid Web, represents a significant security risk for websites relying on this software to manage schedules and events. This specific flaw allows an attacker to perform object injection attacks, which can lead to remote code execution or other severe compromises depending on the context in which the vulnerable application operates. The vulnerability affects versions of The Events Calendar ranging from its initial release up through version 6.17.4, indicating that a substantial portion of installations using legacy or unpatched software are exposed to this threat vector.
At a technical level, the core issue stems from the improper handling of data during the deserialization process. Deserialization is the mechanism by which an application reconstructs serialized objects back into their original state in memory. When an application accepts input that it then passes directly to a deserialization function without adequate validation or sanitization, it creates a pathway for malicious actors to inject crafted payloads. In this specific instance, the vulnerability allows attackers to manipulate the data structure being processed, leading to object injection. This means that instead of receiving benign user inputs such as event titles or dates, the application processes objects created by an attacker with potentially dangerous properties or methods attached.
The operational impact of this vulnerability is severe due to its potential for remote code execution. If the vulnerable classes available in the PHP environment contain magic methods like __wakeup(), __destruct(), or other hooks that execute logic upon deserialization, an attacker can chain these calls to achieve arbitrary command execution on the server hosting the WordPress site. This effectively grants the attacker full control over the underlying system, allowing them to exfiltrate sensitive data, install backdoors, pivot to internal networks, or deface the website. The severity is further amplified by the widespread adoption of The Events Calendar, meaning that a successful exploit could impact thousands of websites simultaneously if they remain on vulnerable versions.
From an industry standards perspective, this vulnerability aligns with CWE-502, which describes Deserialization of Untrusted Data. This category encompasses flaws where applications deserialize data without ensuring its integrity or authenticity, allowing attackers to alter the state of deserialized objects. Furthermore, in terms of attack tactics and techniques, this exploit maps directly to MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter sub-techniques if code execution is achieved, or more broadly to Injection attacks under the Initial Access or Execution kill chain phases. The lack of input validation before deserialization also touches upon CWE-20, Improper Input Validation, which is often a root cause for such high-severity flaws in web applications.
Mitigation strategies must focus on immediate remediation and long-term defensive coding practices. For administrators currently running affected versions, the most critical step is to upgrade The Events Calendar plugin to version 6.17.5 or later, where this vulnerability has been patched by StellarWP. Until an update can be applied, it may be necessary to disable the plugin entirely if event functionality is not immediately required, thereby removing the attack surface from the live environment. Additionally, implementing a Web Application Firewall (WAF) with rules designed to detect anomalous serialization patterns or known exploit signatures for this specific vulnerability can provide a layer of defense in depth while patches are being deployed.
Long-term resilience against such vulnerabilities requires adopting secure coding standards that prioritize safe deserialization practices. Developers should avoid using native PHP functions like unserialize() on user-supplied data whenever possible, opting instead for safer alternatives such as JSON encoding and decoding which do not support object instantiation. If serialization is necessary, strict allow-listing of expected classes must be implemented to prevent the instantiation of arbitrary objects. Regular security audits, static code analysis tools configured to detect unsafe deserialization patterns, and continuous monitoring for unusual server behavior are essential components of a robust defense strategy against this class of vulnerabilities.