Description

Deserialization of Untrusted Data vulnerability in ThemeREX Group Gutentype gutentype allows Object Injection.This issue affects Gutentype: from n/a through 2.1.12.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-10-10T08:17:04.777Z",
  "pubdate": "2026-10-10T08:17:04.777Z",
  "executiveSummary": "The ThemeREX Group Gutentype theme is susceptible to an Object Injection vulnerability caused by the insecure deserialization of untrusted data.\nThis vulnerability exists within the Gutentype theme versions n/a through 2.1.12.\nThe flaw allows an attacker to inject malicious serialized PHP objects into the application, which are then processed by the theme's logic.\nBy manipulating these objects, an attacker can influence application flow, potentially leading to unauthorized operations such as arbitrary file deletion, sensitive data exposure, or remote code execution (RCE) if suitable gadget chains exist within the application's environment.\nThe vulnerability is severe as it bypasses standard input validation mechanisms, enabling an attacker to exert control over the application's internal state.\nExploitation does not necessarily require high-level administrative privileges, though the level of access required for initial entry depends on the specific endpoint exposing the deserialization routine.\nSuccessful exploitation poses significant risks to the confidentiality, integrity, and availability of the affected WordPress site.",
  "technicalDetails": "The vulnerability stems from the application's failure to properly validate or sanitize user-supplied input before passing it to PHP's unserialize() function.\nIn PHP, the unserialize() function converts a string representation of a serialized object back into a PHP object. If the input source is untrusted, an attacker can supply a specially crafted serialized string.\nWhen this string is deserialized, the PHP engine instantiates the object and automatically invokes 'magic methods' if they are present in the class definition, such as __wakeup(), __destruct(), or __toString().\nThese magic methods are executed automatically during the object's lifecycle. An attacker can leverage these methods to initiate a 'gadget chain'—a sequence of existing code patterns within the application or its bundled libraries—to perform unintended actions.\nThe attack flow typically involves identifying an endpoint or input parameter within the Gutentype theme that accepts serialized data. The attacker then constructs a malicious payload containing serialized object structures that align with classes available in the target environment's codebase.\nOnce the payload is transmitted to the vulnerable component, the application executes the insecure deserialization process. The magic methods defined in the attacker-specified classes are triggered, executing the injected instructions.\nThe impact depends heavily on the available classes within the WordPress installation, the active plugins, and the theme itself. A well-crafted exploit can lead to Remote Code Execution (RCE) by leveraging gadgets that manipulate file system operations, database queries, or process execution via system calls.\nFurthermore, since the vulnerable code executes within the context of the web server process, the post-exploitation impact includes the potential for full server compromise, persistent backdoor installation, and unauthorized access to sensitive application configurations or user data stored in the database.\nThe lack of sufficient type-checking or allow-listing during the deserialization process is the primary root cause. Versions of Gutentype from n/a through 2.1.12 fail to implement the necessary security constraints to prevent the instantiation of arbitrary classes, rendering the application vulnerable to object injection attacks."
}