CVE-2022-3906 in Easy Form Builder Plugin
Summary
by MITRE • 12/12/2022
The Easy Form Builder WordPress plugin before 3.4.0 does not sanitise and escape some of its settings, which could allow high privilege users such as admin to perform Stored Cross-Site Scripting attacks even when the unfiltered_html capability is disallowed (for example in multisite setup).
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Analysis
by VulDB Data Team • 04/23/2025
The vulnerability identified as CVE-2022-3906 affects the Easy Form Builder WordPress plugin version 3.4.0 and earlier, representing a critical stored cross-site scripting vulnerability that undermines the security posture of WordPress installations. This flaw exists within the plugin's handling of user settings and configuration data, where insufficient sanitization and escaping mechanisms allow malicious input to persist and execute in the context of other users' browsers. The vulnerability is particularly concerning because it targets high-privilege users such as administrators, who typically possess elevated permissions and access to sensitive system functions. The security implications extend beyond standard user accounts, as administrators are often the primary targets for attackers seeking to establish persistent access or escalate privileges within the WordPress environment.
The technical root cause of this vulnerability stems from the plugin's failure to properly sanitize user-supplied input within its settings management functionality. When administrators configure form builder settings, the plugin stores these values without adequate validation or escaping, creating opportunities for malicious script injection. This vulnerability operates under CWE-79 which classifies the issue as a cross-site scripting flaw, specifically a stored XSS variant where malicious payloads are permanently stored on the server and executed when other users access the affected pages. The flaw becomes particularly dangerous in multisite WordPress configurations where the unfiltered_html capability is typically restricted to prevent arbitrary HTML injection, yet the vulnerability allows bypassing these protections through the plugin's insufficient input handling mechanisms.
The operational impact of CVE-2022-3906 extends beyond immediate script execution capabilities, as successful exploitation can enable attackers to perform a wide range of malicious activities including but not limited to session hijacking, data exfiltration, and privilege escalation within the WordPress environment. Attackers could leverage this vulnerability to inject malicious JavaScript code that would execute whenever administrators view the affected plugin settings, potentially capturing sensitive information, modifying content, or redirecting users to malicious domains. The vulnerability's persistence in stored form configurations means that the malicious code remains active until manually removed or the plugin is updated, providing attackers with extended access windows and potential for long-term compromise of the affected WordPress installations. This threat model aligns with ATT&CK technique T1566 which describes the use of malicious content to gain initial access to systems, and T1059 which encompasses the execution of malicious code through scripting languages.
Mitigation strategies for this vulnerability require immediate attention through plugin version updates to 3.4.0 or later, which contain the necessary sanitization and escaping fixes. System administrators should also implement additional security measures including regular security audits of installed plugins, monitoring for unusual administrative activities, and ensuring that only necessary plugins are installed on production systems. The WordPress multisite configuration should be reviewed to verify that capability restrictions are properly enforced, and administrators should consider implementing additional input validation layers at the web application firewall level. Organizations should also conduct comprehensive vulnerability assessments to identify any other plugins or themes that may exhibit similar sanitization flaws, as this vulnerability pattern suggests potential broader security gaps within the WordPress ecosystem. Regular security training for administrators about the risks of storing untrusted input and the importance of keeping software components updated remains crucial for maintaining overall security hygiene and preventing exploitation of similar vulnerabilities in the future.