CVE-2023-1405 in Formidable Forms Plugin
Summary
by MITRE • 01/16/2024
The Formidable Forms WordPress plugin before 6.2 unserializes user input, which could allow anonymous users to perform PHP Object Injection when a suitable gadget is present.
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Analysis
by VulDB Data Team • 06/11/2025
The vulnerability identified as CVE-2023-1405 affects the Formidable Forms WordPress plugin version 6.2 and earlier, presenting a critical security risk through improper input handling mechanisms. This flaw exists within the plugin's architecture where user-supplied data undergoes unserialization processes without adequate sanitization or validation, creating an avenue for malicious actors to exploit the system through PHP Object Injection attacks. The vulnerability specifically targets the plugin's handling of serialized data structures that are processed during form submissions or other user interactions, potentially allowing attackers to execute arbitrary code on the affected WordPress installation.
The technical implementation of this vulnerability stems from the plugin's failure to properly validate and sanitize user input before processing serialized data structures. When the plugin encounters serialized objects in user submissions, it performs unserialization operations that can trigger PHP object injection attacks. This occurs because the plugin does not implement proper input validation mechanisms or secure deserialization practices. Attackers can craft malicious serialized objects that, when processed by the vulnerable plugin, can execute arbitrary code on the server. The vulnerability becomes particularly dangerous when combined with existing gadget chains within the PHP environment or the WordPress ecosystem, which can amplify the attack surface and enable more sophisticated exploitation techniques.
The operational impact of CVE-2023-1405 extends beyond simple code execution, potentially allowing attackers to gain full control over affected WordPress installations. This vulnerability can be exploited by anonymous users without requiring authentication, making it particularly dangerous for publicly accessible websites. Successful exploitation could result in complete compromise of the affected system, including data theft, defacement, or the installation of backdoors. The attack vector typically involves crafting malicious form submissions or API calls that contain specially crafted serialized objects designed to trigger the injection mechanism. Organizations running vulnerable versions of the Formidable Forms plugin face significant risk of unauthorized access and potential data breaches, especially if the affected systems lack proper network segmentation or monitoring controls.
Mitigation strategies for CVE-2023-1405 primarily focus on immediate remediation through plugin updates to version 6.2 or later, which includes patches addressing the unserialization vulnerability. System administrators should also implement additional security controls such as input validation, secure deserialization practices, and monitoring of suspicious form submissions. The vulnerability aligns with CWE-502, which specifically addresses "Deserialization of Untrusted Data," and can be mapped to ATT&CK technique T1505.003 for "Exploitation for Privilege Escalation" and T1059.007 for "Command and Scripting Interpreter: PowerShell." Organizations should also consider implementing web application firewalls, restricting form submission capabilities, and conducting regular security assessments to identify potential exploitation vectors. The remediation process should include thorough testing of the updated plugin to ensure compatibility with existing forms and functionality while maintaining security integrity throughout the upgrade process.