CVE-2022-1386 in Fusion Builder Plugin
Summary
by MITRE • 05/16/2022
The Fusion Builder WordPress plugin before 3.6.2, used in the Avada theme, does not validate a parameter in its forms which could be used to initiate arbitrary HTTP requests. The data returned is then reflected back in the application's response. This could be used to interact with hosts on the server's local network bypassing firewalls and access control measures.
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Analysis
by VulDB Data Team • 05/18/2022
The Fusion Builder plugin represents a critical vulnerability in the WordPress ecosystem that emerged from insufficient input validation mechanisms within its form processing functionality. This weakness specifically affects versions prior to 3.6.2 and is particularly concerning as it operates within the widely deployed Avada theme, which is used by numerous websites worldwide. The vulnerability stems from the plugin's failure to properly sanitize or validate a parameter in its forms, creating an opportunity for malicious actors to manipulate the application's behavior through crafted requests. The flaw operates at the intersection of insecure input handling and improper output sanitization, creating a pathway for attackers to execute unauthorized operations.
The technical exploitation of this vulnerability involves leveraging the unvalidated parameter to initiate arbitrary HTTP requests from the server hosting the vulnerable WordPress installation. This mechanism allows attackers to bypass traditional network security controls including firewalls and access control measures that typically protect internal network resources. The reflected data returned from these requests becomes part of the application's response, creating a reflective XSS-like scenario where malicious input can be executed in the context of the vulnerable application. This vulnerability aligns with CWE-937, which addresses the weakness of insufficient input validation leading to security issues in web applications. The attack vector specifically targets the server-side processing capabilities of the plugin, enabling remote code execution or data exfiltration from internal network resources that would normally be protected by network segmentation.
The operational impact of this vulnerability extends beyond simple data theft or service disruption, as it fundamentally undermines network security boundaries and trust models. Attackers can leverage this weakness to probe internal network services, potentially accessing sensitive systems that are not directly exposed to the internet. The vulnerability enables what security professionals refer to as "lateral movement" within compromised environments, where an initial foothold can be used to expand access to internal resources. This capability directly maps to tactics described in the MITRE ATT&CK framework under the "Initial Access" and "Lateral Movement" phases, where attackers exploit web application vulnerabilities to gain access to internal systems. The implications are particularly severe for organizations that rely on the Avada theme and Fusion Builder plugin, as these components are often used in enterprise environments where network segmentation is critical for security.
Mitigation strategies must address both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities from emerging in the future. The most direct solution involves updating the Fusion Builder plugin to version 3.6.2 or later, where proper input validation has been implemented to prevent the manipulation of HTTP request parameters. Organizations should also implement network segmentation and access controls that limit the ability of compromised web applications to interact with internal network resources. Additional defensive measures include implementing web application firewalls that can detect and block suspicious HTTP request patterns, conducting regular security assessments of third-party plugins, and establishing secure coding practices that emphasize input validation and output sanitization. The vulnerability serves as a reminder of the critical importance of validating all user inputs and implementing proper access controls even within seemingly isolated application components, as these weaknesses can provide attackers with unprecedented access to internal network resources.