CVE-2026-110383 in Electronic Signature Add-on Plugin
Summary
by MITRE • 10/18/2026
Authorization Bypass Through User-Controlled Key vulnerability in WP E-Signature Electronic Signature Add-on for Fluent Forms signature-fluent-contract-forms-add-on allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects Electronic Signature Add-on for Fluent Forms: from n/a through 2.0.5.
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Analysis
by VulDB Data Team • 10/18/2026
The vulnerability identified as an Authorization Bypass Through User-Controlled Key within the WP E-Signature Electronic Signature Add-on for Fluent Forms represents a critical failure in access control mechanisms. This flaw specifically affects versions of the plugin ranging from its initial release through version 2.0.5. The core issue stems from how the application handles user-supplied input when determining resource ownership or permission levels, allowing an attacker to manipulate keys or identifiers associated with signed documents or contract forms. By exploiting incorrectly configured access control security levels, a malicious actor can bypass intended restrictions and interact with resources that should be inaccessible to their privilege level. This type of vulnerability is fundamentally rooted in the application's failure to properly validate whether the authenticated user has legitimate authority over the specific data object they are attempting to modify or view.
From a technical perspective, this flaw aligns closely with CWE-284 Improper Access Control and CWE-639 Authorization Bypass Through User-Controlled Key. The vulnerability arises because the software relies on client-side provided identifiers or server-side variables that can be tampered with via HTTP requests without sufficient backend verification against the current user's session permissions. In typical implementations of such plugins, when a user attempts to view, edit, download, or delete an electronic signature document, the application checks if the request originates from a valid session and then verifies ownership based on provided IDs. If this check is flawed, an attacker can simply alter these identifiers in their requests to access documents belonging to other users or administrative accounts. This bypasses the intended security boundaries established by the plugin's role-based access control system, effectively granting unauthorized entities elevated privileges within the WordPress environment.
The operational impact of this vulnerability is severe for organizations relying on Fluent Forms and its electronic signature add-on for sensitive contractual agreements. Since these plugins handle legally binding documents containing personally identifiable information (PII), financial data, or proprietary business terms, an authorization bypass allows attackers to exfiltrate confidential data without authentication. Furthermore, the ability to manipulate access controls may enable unauthorized modifications to existing contracts or the creation of fraudulent signatures if write permissions are also compromised. This not only violates privacy regulations such as GDPR or CCPA but also exposes organizations to significant legal liability and reputational damage. The lack of proper enforcement means that any authenticated user with low-level privileges could potentially escalate their access, leading to a complete compromise of the integrity and confidentiality of the digital signature workflow managed by the application.
To mitigate this risk, immediate action is required for all administrators running affected versions of the WP E-Signature Electronic Signature Add-on. The primary remediation step is to upgrade the plugin to version 2.0.6 or later, where the developers have addressed the improper access control logic and implemented stricter validation checks on user-controlled keys. Until an update can be applied, organizations should consider disabling the electronic signature functionality if it is not actively required for business operations. Additionally, implementing a Web Application Firewall (WAF) with rules targeting parameter tampering in form submission endpoints may provide a layer of defense against exploitation attempts by blocking requests that attempt to modify critical identifiers associated with document ownership. Regular security audits and penetration testing should also be conducted to ensure no other similar vulnerabilities exist within the broader WordPress ecosystem, particularly those related to REST API endpoint permissions or file access controls.