CVE-2026-73993 in FundEngine Plugin
Summary
by MITRE • 08/20/2026
Unauthenticated PHP Object Injection in FundEngine <= 1.7.9 versions.
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Analysis
by VulDB Data Team • 08/20/2026
The vulnerability identified as an unauthenticated PHP object injection flaw within FundEngine versions prior to or equal to 1.7.9 represents a critical security deficiency that allows attackers to execute arbitrary code on the target server without requiring valid credentials. This type of vulnerability stems from the improper handling of user-supplied input during the deserialization process, where data is converted back into PHP objects. In many modern web applications, serialization is used extensively for session management, caching mechanisms, and passing complex data structures between different parts of an application or across network boundaries. When these serialized strings are derived directly from untrusted sources such as HTTP request parameters, cookies, or headers without adequate validation or sanitization, they become a prime vector for exploitation. The attacker can craft a maliciously formatted serialized string that, when processed by the vulnerable application, triggers the instantiation of specific PHP classes with pre-defined properties and methods designed to perform harmful actions.
The technical root cause lies in the presence of magic methods within the PHP classes utilized by FundEngine, such as __wakeup(), __destruct(), or __call(). These special functions are automatically invoked during deserialization if certain conditions are met. By manipulating the serialized payload, an attacker can control which class is instantiated and what values its properties hold. If the application includes files containing these vulnerable classes without checking their origin, it becomes possible to leverage existing functionality within those classes for unintended purposes. This technique is often referred to as a gadget chain, where multiple benign methods are chained together to achieve a malicious outcome, such as remote code execution or file inclusion. The absence of authentication requirements significantly lowers the barrier to entry for attackers, allowing anyone with network access to attempt exploitation without needing to bypass login mechanisms or steal session tokens first.
From an operational perspective, the impact of this vulnerability is severe and potentially catastrophic. Successful exploitation can lead to complete compromise of the underlying server infrastructure. Attackers may gain shell access, read sensitive configuration files containing database credentials or API keys, modify application data, or install backdoors for persistent access. In a financial context implied by the name FundEngine, such a breach could result in unauthorized transactions, theft of funds, manipulation of investment records, and exposure of personally identifiable information belonging to clients. The lack of authentication means that automated scanning tools can easily discover and exploit this flaw across large networks, leading to widespread compromise if patches are not applied promptly. Furthermore, because the attack does not require user interaction beyond sending a crafted HTTP request, it is highly scalable and difficult to detect through traditional signature-based intrusion detection systems unless specific behavioral anomalies in deserialization processes are monitored.
To mitigate this risk, immediate action must be taken by upgrading FundEngine to version 1.8.0 or later where the vulnerability has been addressed. In addition to updating software, developers should implement strict input validation and type checking for all data involved in serialization operations. It is crucial to avoid deserializing user-controlled data entirely if possible; instead, use secure formats like JSON which do not support object instantiation during parsing. If deserialization of untrusted data is unavoidable, implementing a whitelist-based approach that restricts the types of objects allowed to be instantiated can prevent exploitation of unexpected classes. Additionally, enabling strict error reporting in development environments and using static analysis tools can help identify unsafe serialization practices early in the software development lifecycle. Monitoring server logs for unusual patterns related to PHP object instantiation or file system access can also aid in detecting ongoing attempts at exploitation.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-502, which describes Deserialization of Untrusted Data. It is frequently associated with attack techniques documented in the MITRE ATT&CK framework under T1059 Command and Scripting Interpreter or T1068 Privilege Escalation, depending on how the injected code interacts with the operating system and application permissions. Understanding these mappings helps security teams prioritize remediation efforts based on established industry standards for vulnerability management. Organizations should also consider implementing Web Application Firewalls configured to detect patterns indicative of PHP object injection attempts as an additional layer of defense while patching is underway. Regular penetration testing focused on input validation and serialization handling will further strengthen the application's resilience against similar future threats.