Description

Deserialization of Untrusted Data vulnerability in ThemeREX Group Hygia hygia allows Object Injection.This issue affects Hygia: from n/a through 1.21.0.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-10-10T08:17:06.187Z",
  "pubdate": "2026-10-10T08:17:06.187Z",
  "executiveSummary": "A critical Deserialization of Untrusted Data vulnerability has been identified in ThemeREX Group Hygia (hygia), affecting all versions from n/a through 1.21.0. This security flaw enables remote attackers to perform Object Injection against the underlying PHP application environment.\nThe core risk stems from the application processing untrusted, user-supplied serialized data without sufficient validation. Successful exploitation allows an attacker to inject arbitrary PHP objects into the application memory space. Depending on the presence of usable Property-Oriented Programming (POP) chains within the application codebase, active plugins, or underlying libraries, an attacker could potentially achieve remote code execution (RCE), arbitrary file deletion, unauthorized database access, or full compromise of the target system.\nExploitation requirements depend on the exposure of the vulnerable endpoint, but deserialization flaws frequently allow unauthenticated remote attackers to submit malicious payloads via HTTP request parameters, headers, or cookies. Organizations utilizing ThemeREX Group Hygia version 1.21.0 or earlier are strongly advised to audit their environments and apply vendor patches immediately.",
  "technicalDetails": "The underlying root cause of this vulnerability lies in improper input handling prior to invoking PHP deserialization functions within ThemeREX Group Hygia. When an application accepts serialized objects from untrusted sources via HTTP parameters or request bodies and processes them using functions like native unserialize(), the PHP engine automatically reconstructs the object structures in memory based on the string representation supplied by the client.\nDuring the object instantiation and destruction lifecycle, PHP automatically executes specific magic methods—such as __wakeup(), __destruct(), __toString(), __call(), or __get()—associated with the injected class structures. If an attacker crafts a payload utilizing classes already defined within the global PHP execution context (a POP chain), these magic methods can be chained together to invoke sensitive internal functions with attacker-controlled properties.\nThe attack flow typically follows a defined progression: First, the adversary analyzes the target application or public components to identify an HTTP interface exposed by ThemeREX Group Hygia (versions through 1.21.0) that accepts serialized input. Second, the attacker constructs a specialized serialized PHP object payload designed to trigger a specific execution path upon deserialization. Third, the payload is transmitted to the target server via an HTTP request.\nUpon receiving the request, the application passes the untrusted input directly into the deserialization routine without verifying its integrity or restricting allowed classes. As PHP parses the string, the injected objects are instantiated. As execution completes or memory management reclaims the objects, the PHP runtime automatically executes the associated magic methods using the malicious properties embedded in the payload.\nThe post-exploitation impact is dictated by the available POP chains in the host environment. If suitable object chains exist within ThemeREX Group Hygia, the core platform, or associated modules, the attacker can achieve arbitrary code execution in the context of the web server process. This allows complete takeover of the application, unauthorized data exfiltration, local file inclusion or deletion, and potential lateral movement across the internal hosting network."
}