CVE-2026-80513 in wpForo Forum Plugin
Summary
by MITRE • 09/24/2026
The wpForo Forum WordPress plugin before 3.1.6 does not restrict which classes may be instantiated when it deserializes a user-supplied profile field value, allowing authenticated users with Subscriber-level access and above to inject a PHP Object. No POP chain is present in the wpForo Forum WordPress plugin before 3.1.6 itself; if one is present via another installed wpForo Forum WordPress plugin before 3.1.6 or , this could lead to remote code execution, arbitrary file operations, or SQL injection. This is an incomplete fix of CVE-2026-49769.
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Analysis
by VulDB Data Team • 09/24/2026
The vulnerability identified in the wpForo Forum WordPress plugin prior to version 3.1.6 represents a critical security flaw rooted in improper handling of PHP object deserialization. Specifically, the application fails to restrict which classes can be instantiated when processing user-supplied profile field values during the unserialization process. This lack of validation allows authenticated users with Subscriber-level access or higher privileges to inject arbitrary PHP objects into the system. The core technical failure lies in the absence of a whitelist mechanism for class names, enabling attackers to manipulate the internal state of application objects by providing serialized payloads that reference dangerous classes available within the WordPress environment or other installed plugins.
While the wpForo Forum plugin itself does not contain any built-in PHP Object Poisoning (POP) chains capable of directly causing remote code execution, the vulnerability remains severe due to its role as a vector for exploiting components present in the broader ecosystem. If an attacker can inject objects that interact with classes from other installed plugins or core WordPress files that do possess exploitable POP chains, they may achieve arbitrary file operations, SQL injection, or full remote code execution on the target server. This indirect exploitation path underscores the danger of insecure deserialization practices even when the immediate component lacks direct exploitability, as it serves as a bridge to more dangerous functionalities elsewhere in the application stack.
This issue is classified under CWE-502, which denotes Deserialization of Untrusted Data, and aligns with MITRE ATT&CK technique T1648, Exploitation for Privilege Escalation or Defense Evasion via Insecure Deserialization. The vulnerability serves as an incomplete fix for CVE-2026-49769, indicating that previous remediation efforts failed to fully address the root cause of untrusted data handling in profile fields. Attackers with low-level access can leverage this flaw to escalate privileges or pivot into more critical system components, effectively bypassing intended security boundaries through object manipulation rather than direct code injection.
To mitigate this risk, administrators must immediately upgrade the wpForo Forum plugin to version 3.1.6 or later, where proper input validation and class whitelisting for deserialization operations have been implemented. Additionally, organizations should audit their WordPress environments for other plugins that may expose similar insecure deserialization vulnerabilities, as these can be chained with this flaw to increase impact. Implementing strict content security policies and monitoring logs for unusual serialization patterns or unexpected object instantiations can further enhance detection capabilities. Regular vulnerability assessments focusing on PHP application logic are essential to prevent exploitation of such indirect attack vectors in complex plugin ecosystems.