CVE-2024-8016

The vulnerability in the Events Calendar Pro plugin for WordPress stems from improper handling of user input, specifically through the deserialization of untrusted data from the 'filters' parameter in widgets. This flaw allows for PHP Object Injection, which can lead to the execution of arbitrary code on the server. The vulnerability is particularly concerning because it affects all versions up to and including 7.0.2, making it a widespread issue. When an attacker successfully injects a malicious PHP object, they can manipulate the application's behavior, potentially leading to a full compromise of the affected WordPress site. The presence of a Property-Oriented Programming (POP) chain further exacerbates the risk, as it enables attackers to craft payloads that can execute code remotely, thereby increasing the potential impact of the vulnerability.

Exploitation of this vulnerability can occur through various attack vectors, primarily targeting authenticated users with administrator-level access. However, the situation becomes more alarming when considering specific configurations, such as when the plugin is used in conjunction with Elementor. In these scenarios, even users with lower privileges, such as those with contributor-level access, may be able to exploit the vulnerability. Attackers could leverage social engineering tactics to gain access to accounts with the necessary permissions or exploit weak password policies to elevate their privileges. Once inside, they could inject malicious objects through the filters parameter, leading to unauthorized access and control over the WordPress installation.

The real-world impact of this vulnerability can be significant, particularly for businesses relying on WordPress for their online presence. A successful attack could result in unauthorized access to sensitive data, defacement of the website, or even the deployment of malware that could affect visitors. The potential for data breaches can lead to severe reputational damage, loss of customer trust, and financial repercussions, including regulatory fines if personal data is compromised. Additionally, the operational disruption caused by a successful exploit can lead to downtime, further affecting revenue and customer relationships. Organizations must recognize that the consequences of such vulnerabilities extend beyond immediate technical concerns and can have long-lasting effects on their business operations.

To detect and mitigate this vulnerability, organizations should implement a multi-faceted approach. Regularly updating the Events Calendar Pro plugin to the latest version is crucial, as it ensures that any known vulnerabilities are patched. Additionally, employing web application firewalls (WAFs) can help filter out malicious requests that attempt to exploit the vulnerability. Conducting regular security audits and penetration testing can also identify potential weaknesses in the system before they can be exploited. Furthermore, organizations should enforce strict access controls, ensuring that only users with the necessary permissions can access sensitive features of the plugin. Educating users about the importance of strong passwords and the risks associated with social engineering can also help reduce the likelihood of an attack.

In conclusion, the vulnerability in the Events Calendar Pro plugin represents a serious risk to WordPress installations, particularly when considering the potential for exploitation by users with varying levels of access. The implications for businesses are profound, encompassing both technical and reputational damage. By adopting proactive detection and mitigation strategies, organizations can better protect themselves against this and similar vulnerabilities, ensuring the integrity and security of their online platforms.

The CVSS score for CVE-2024-8016 has been revised upward from 7.2 to 9.1, reflecting a reassessment of the vulnerability’s impact and exploitability. This adjustment underscores the critical nature of the PHP Object Injection flaw in the Events Calendar Pro plugin, particularly given the presence of a gadget chain enabling remote code execution. Although our telemetry indicates a slight decline in the Exploit Prediction Scoring System (EPSS) value, the vulnerability remains in the upper decile for exploitation likelihood, signaling persistent risk. Importantly, no new exploit techniques or proof-of-concept code have been detected in the wild, suggesting that while the vulnerability is severe, active exploitation has not markedly increased. For defenders, the heightened CVSS score demands renewed prioritization in patch management and monitoring, especially in environments where administrative or elevated user access is common. The recalibrated risk level confirms that this vulnerability poses a critical threat vector that could facilitate full system compromise if exploited, reinforcing its status as a top-tier security concern.

Update 2 — May 21, 2026

The recent downward revision of the CVSS score for CVE-2024-8016 from 9.1 to 7.2 reflects a refined understanding of the vulnerability’s exploitability and impact. This adjustment stems from updated analysis indicating that while the vulnerability remains serious, its practical exploitation conditions are more constrained than initially assessed, primarily requiring authenticated administrator-level access or higher. CSURFACE threat intelligence confirms that no new exploitation techniques or proof-of-concept code have surfaced, and our telemetry shows a stable exploitation trend without any marked escalation. The EPSS score remains moderate, suggesting a steady but not rapidly increasing likelihood of exploitation. For defenders, this recalibration signals a nuanced risk profile: the vulnerability continues to pose a significant threat, particularly in environments with privileged user exposure, but the immediate risk of widespread exploitation is somewhat reduced. Consequently, the threat level remains high but not critical, emphasizing the importance of targeted monitoring and access control rather than broad emergency response.