CVE-2026-84752 in RTMKit Plugin
Summary
by MITRE • 09/03/2026
Contributor PHP Object Injection in RTMKit <= 2.1.5 versions.
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Analysis
by VulDB Data Team • 09/03/2026
The vulnerability identified as Contributor PHP Object Injection in RTMKit versions up to and including 2.1.5 represents a critical security flaw rooted in the improper handling of user-supplied input within the application's object instantiation logic. This type of attack, commonly referred to as Insecure Deserialization or Direct Object Reference leading to deserialization issues, allows an attacker to manipulate serialized PHP objects that are passed through HTTP parameters, cookies, or POST data. When the RTMKit plugin processes these inputs without adequate validation or sanitization, it inadvertently triggers the __wakeup() magic method or other unserialization functions on maliciously crafted object graphs. This behavior deviates from secure coding practices by trusting external input as executable code structure rather than treating it strictly as data, thereby bypassing intended access controls and logic flows within the WordPress environment where RTMKit operates.
From a technical perspective, this flaw aligns with CWE-502, which describes Deserialization of Untrusted Data. The core issue lies in the application's failure to verify the integrity or origin of the serialized data before processing it. In PHP environments, objects can contain properties that reference other classes or methods. By carefully constructing a payload containing a gadget chain—a sequence of existing classes and their method calls within the target environment—an attacker can force the application to execute arbitrary functions. This is particularly dangerous in WordPress plugins because they often run with elevated privileges relative to standard user roles, meaning successful exploitation can lead to significant compromise of the underlying server infrastructure rather than just isolated data leakage.
The operational impact of this vulnerability is severe and multifaceted. An authenticated attacker, or potentially an unauthenticated one depending on specific endpoint exposure within RTMKit, can achieve Remote Code Execution (RCE). This capability allows for complete control over the web application's context, including reading sensitive configuration files such as wp-config.php to extract database credentials, modifying site content, installing backdoors, and pivoting to attack other systems on the internal network. Furthermore, because WordPress plugins are widely deployed, this vulnerability poses a risk of widespread compromise across numerous websites if left unpatched. The attacker can also escalate privileges by manipulating session data or bypassing role-based access controls inherent in the CMS architecture, effectively turning a minor plugin flaw into a full-site takeover scenario.
Mitigation strategies must focus on immediate remediation and long-term defensive posture improvements. The primary recommendation is to upgrade RTMKit to version 2.1.6 or later, where this specific deserialization vector has been addressed by developers through stricter input validation and the removal of unsafe unserialization calls. For organizations unable to patch immediately due to compatibility constraints, implementing a Web Application Firewall (WAF) rule set that detects common PHP serialization patterns in HTTP requests can provide temporary protection against exploitation attempts. Additionally, enforcing strict Content Security Policies and ensuring that server-side configurations disable dangerous functions like unserialize() where not explicitly required by the application logic are vital steps. Regular security audits focusing on CWE-502 and adherence to OWASP Top 10 guidelines regarding insecure deserialization will help prevent similar vulnerabilities in future development cycles.
This incident underscores the importance of secure coding practices within third-party plugin ecosystems, which often serve as attack vectors for broader infrastructure compromises. The mapping to MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter via PHP, highlights how this vulnerability facilitates lateral movement and persistence on compromised hosts. Security teams should monitor server logs for unusual activity related to object instantiation or unexpected file modifications following any update to RTMKit versions prior to 2.1.6. Continuous monitoring and proactive patch management are essential components of a robust defense-in-depth strategy against such application-layer vulnerabilities that exploit the dynamic nature of interpreted languages like PHP.