Description

Deserialization of Untrusted Data vulnerability in Tainacan Community Tainacan tainacan allows Object Injection.This issue affects Tainacan: from n/a through 1.3.0.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.2",
  "pubDate": "2026-10-10T14:16:38.130Z",
  "pubdate": "2026-10-10T14:16:38.130Z",
  "executiveSummary": "A deserialization of untrusted data vulnerability exists in the Tainacan plugin for WordPress, specifically affecting all versions from n/a through 1.3.0.\nThis vulnerability is classified as an Object Injection flaw, which occurs when application logic processes serialized objects from user-controlled input without sufficient validation or sanitization.\nThe primary risk associated with this vulnerability is the potential for Remote Code Execution (RCE) or other forms of arbitrary code execution within the WordPress environment.\nAn unauthenticated or authenticated attacker capable of supplying serialized data to the application can trigger the instantiation of arbitrary classes present in the system, potentially altering application behavior or executing malicious payloads.\nGiven that deserialization vulnerabilities often lead to full system compromise by leveraging PHP magic methods (such as __destruct, __wakeup, or __toString) present in available classes within the codebase or included libraries, the security impact is classified as critical.\nThe vulnerability necessitates immediate remediation to prevent unauthorized remote exploitation, as it bypasses standard input security controls through the abuse of PHP object manipulation mechanisms.",
  "technicalDetails": "The vulnerability resides in the core implementation of the Tainacan plugin, which handles serialized data in a manner that allows untrusted input to influence the application's object lifecycle. Deserialization of untrusted data occurs when an application takes user-provided input that has been serialized—typically via PHP's serialize() function—and passes it to unserialize() without strict verification.\nIn the context of the Tainacan plugin, the application fails to validate the structure or the content of the serialized payload before processing it. This vulnerability allows an attacker to inject a crafted serialized object into the application state.\nThe exploitation mechanism relies on a 'POP chain' (Property-Oriented Programming). When the PHP interpreter unserializes the malicious payload, it reconstructs the specified object. During this reconstruction, PHP invokes magic methods if they exist within the defined class. If the attacker targets a class already loaded in the application's memory that contains a magic method (e.g., __destruct(), __wakeup(), or __toString()) that performs sensitive operations—such as file manipulation, database interaction, or function calling—the attacker can influence these operations.\nThe attack flow proceeds as follows: 1. Identification of the vulnerable input vector through which serialized data is passed to the Tainacan plugin. 2. Creation of a malicious serialized PHP object designed to target a specific 'gadget' class available within the Tainacan plugin or the broader WordPress environment. 3. Transmission of the payload to the vulnerable endpoint. 4. Triggering of the unserialization process by the server. 5. Execution of the POP chain, leading to the intended malicious effect, such as writing arbitrary files, bypassing authentication, or achieving Remote Code Execution.\nThe vulnerability affects Tainacan versions from n/a through 1.3.0. Because the application logic does not impose a restriction on the classes that can be instantiated during the unserialization process, it effectively provides a primitive that can be leveraged to execute code with the permissions of the web server user. This bypasses typical WordPress input sanitization routines, as the exploit payload is technically a valid serialized string, which often evades basic signature-based Web Application Firewall (WAF) rules that look for common web-based attack patterns. Post-exploitation, an attacker could maintain persistence, exfiltrate the WordPress database, or escalate privileges within the CMS."
}