Description

Subscriber PHP Object Injection in Conversational Forms for ChatBot <= 1.5.0 versions.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.8",
  "pubDate": "2026-09-30T13:17:28.587Z",
  "pubdate": "2026-09-30T13:17:28.587Z",
  "executiveSummary": "A critical PHP Object Injection vulnerability exists in the Conversational Forms for ChatBot plugin, versions 1.5.0 and below. This security flaw allows unauthenticated or low-privileged users to pass serialized objects to vulnerable entry points, which are subsequently unserialized by the application without adequate validation.\nThe vulnerability stems from the improper handling of user-supplied input that is passed to the PHP unserialize() function. Successful exploitation allows an attacker to manipulate the internal state of objects within the application, leading to severe consequences such as arbitrary code execution (ACE), unauthorized file access, or full system compromise.\nBecause the plugin is designed to process conversational form data, the attack surface is exposed via standard web request parameters. The risk profile is high, as it does not necessarily require complex authentication bypasses if the injection point is accessible to subscribers or guest users. Organizations utilizing this plugin are at risk of complete site takeover if an attacker crafts a malicious POP (Property-Oriented Programming) chain using available classes within the application or its dependencies.",
  "technicalDetails": "The vulnerability is rooted in the insecure use of the PHP unserialize() function on user-controlled input within the Conversational Forms for ChatBot plugin. When a PHP application unserializes data provided by a user, it triggers the instantiation of objects defined within the application's scope. If an attacker controls the serialized string, they can specify the class to be instantiated and the values assigned to its properties.\nThe attack flow initiates when the attacker identifies a parameter that accepts serialized PHP data, which is then passed directly into a vulnerable function call. By crafting a specific serialized payload, an attacker can leverage existing classes within the WordPress environment or the plugin itself to construct a 'POP chain.' This involves chaining together magic methods—such as __destruct(), __wakeup(), or __toString()—already present in the codebase to achieve unintended side effects.\nIn the context of this plugin, an attacker can perform the following steps to exploit the vulnerability: First, they identify the specific input parameter responsible for handling serialized form configuration or session data. Second, they analyze the codebase to identify 'gadget' classes that perform sensitive operations (e.g., file deletion, database queries, or command execution) upon object destruction or property initialization. Third, the attacker crafts a serialized payload designed to trigger these gadgets sequentially.\nUpon transmission of the malicious payload, the application's unserialization process triggers the attacker's defined gadget chain. Since the plugin performs this deserialization without verifying the integrity or origin of the data, the underlying server will execute the logic embedded in the gadget chain with the privileges of the web server process. This effectively bypasses standard access control mechanisms, as the execution occurs during the object's lifecycle management rather than through a traditional function invocation.\nImpacts following successful exploitation include remote code execution (RCE) via system-level functions, the ability to overwrite critical application configuration files, or the potential for privilege escalation by modifying user metadata objects stored within the serialized stream. Because this affects versions up to 1.5.0, the vulnerability remains a primary concern for any site using legacy configurations of the ChatBot plugin. The exposure is heightened by the fact that the injection can often be executed over the network without requiring administrative privileges, making it a high-priority risk for web application security."
}