CVE-2023-5416 in Funnelforms Free Plugin
Summary
by MITRE • 11/22/2023
The Funnelforms Free plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the fnsf_delete_category function in versions up to, and including, 3.4. This makes it possible for authenticated attackers, with subscriber-level permissions and above, to delete categories.
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Analysis
by VulDB Data Team • 04/11/2026
The Funnelforms Free plugin for WordPress presents a critical authorization vulnerability that undermines the integrity of content management systems. This flaw exists within the fnsf_delete_category function where proper capability validation is absent, allowing attackers with minimal privileges to manipulate the plugin's data structures. The vulnerability affects all versions up to and including 3.4, creating a persistent risk for WordPress installations that rely on this plugin for form management and lead capture functionality. The issue represents a direct violation of the principle of least privilege, where users should only have access to functions commensurate with their assigned roles and permissions.
The technical exploitation of this vulnerability occurs through the absence of capability checks that should normally validate user permissions before executing destructive operations. When an authenticated attacker with subscriber-level privileges attempts to delete a category, the system fails to verify whether the user possesses the necessary administrative rights to perform such an action. This missing validation creates an authorization bypass that enables unauthorized data modification, potentially leading to complete disruption of form categories and associated lead data. The vulnerability stems from improper input validation and access control implementation, making it particularly dangerous in multi-user environments where different permission levels exist. This weakness aligns with CWE-284, which addresses improper access control mechanisms in software applications.
The operational impact of this vulnerability extends beyond simple data deletion, as it can compromise the entire lead capture and form management infrastructure. Attackers can exploit this flaw to remove critical form categories, thereby disrupting the flow of leads and potentially causing significant business disruption. The ability to delete categories without proper authorization also creates opportunities for data corruption and can be leveraged as part of broader attack campaigns targeting WordPress installations. This vulnerability particularly affects organizations that rely heavily on form-based data collection, as the deletion of form categories can result in complete loss of lead information and compromise the effectiveness of marketing automation efforts. The attack surface is further expanded when considering that subscribers typically have limited access to core WordPress functionality, making this unauthorized access particularly concerning from a security perspective.
Organizations should immediately implement mitigation strategies to address this vulnerability, beginning with immediate plugin updates to versions that contain the necessary capability checks. The recommended approach involves upgrading to the latest plugin version where the missing authorization validation has been implemented. Security administrators should also consider implementing additional access controls through custom code modifications or security plugins that can enforce stricter validation of user permissions before allowing category deletion operations. Monitoring and logging of administrative actions should be enhanced to detect unauthorized attempts to modify form categories. This vulnerability demonstrates the importance of regular security audits and the need for continuous monitoring of third-party plugins that may introduce security risks into WordPress environments. The remediation process should include comprehensive testing to ensure that the updated plugin functions correctly while maintaining proper access controls. Organizations should also review their overall WordPress security posture, including user permission management and regular security updates, to prevent similar vulnerabilities from emerging in other components of their web infrastructure.