CVE-2026-80438 in Ninja Forms Plugin
Summary
by MITRE • 09/04/2026
The Ninja Forms WordPress plugin before 3.15.2 does not restrict its REST abilities to administrators, accepting a Ninja Forms WordPress plugin before 3.15.2-specific capability as equivalent to full site administration, which allows any user granted that capability to read Ninja Forms WordPress plugin before 3.15.2 settings and stored form submissions, overwrite the Ninja Forms WordPress plugin before 3.15.2's configuration, and create or modify arbitrary posts and pages. The capability belongs to no default WordPress role and the Ninja Forms WordPress plugin before 3.15.2 never grants it, so an administrator must have assigned it, typically when delegating access to the form builder.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in Ninja Forms versions prior to 3.15.2 represents a critical authorization flaw within the plugin's REST API implementation. This issue stems from an improper restriction of administrative capabilities, where specific internal permissions are incorrectly treated as equivalent to full site administration rights. In standard WordPress architecture, access control is typically managed through roles and capabilities that map to distinct levels of privilege. However, in this instance, the plugin fails to enforce strict boundaries on who can invoke certain REST endpoints. Consequently, any user account assigned a capability intended for form management or editing is inadvertently granted powers far exceeding those originally scoped by the system administrator. This misconfiguration allows users with relatively low-level access to interact with sensitive backend functions that should be reserved exclusively for high-privilege accounts such as administrators.
The technical core of this vulnerability lies in how the plugin handles capability checks during REST API requests. Instead of validating whether the requesting user holds a role explicitly authorized for administrative actions, the code accepts a specific Ninja Forms-specific capability and treats it as sufficient proof of full site administration rights. This logic error effectively bypasses WordPress's native permission layers. As a result, authenticated users who have been granted this delegated capability can execute operations that modify core plugin settings, access confidential data, and manipulate content across the entire website. The flaw is particularly dangerous because it relies on an administrative action to activate; since no default WordPress role possesses this specific capability, an administrator must explicitly assign it to a user or role, typically when delegating form-building responsibilities. This means the vulnerability only becomes exploitable after an admin has attempted to grant limited access for legitimate purposes, inadvertently creating a backdoor with elevated privileges.
The operational impact of this flaw is severe and multifaceted. First, attackers can read sensitive Ninja Forms settings and stored form submissions. These submissions often contain personally identifiable information (PII) such as names, email addresses, phone numbers, and potentially financial or health-related data depending on the forms deployed. The exposure of this data constitutes a significant privacy violation and may lead to non-compliance with regulations like GDPR or HIPAA if applicable. Second, attackers can overwrite the plugin's configuration files, which could disrupt site functionality, alter form behavior in malicious ways, or disable security features implemented by other plugins. Third, and most critically, the ability to create or modify arbitrary posts and pages allows for defacement, phishing page creation, or further exploitation of the WordPress installation through injected scripts or links. This level of control effectively compromises the integrity and availability of the entire web application.
From a classification perspective, this vulnerability aligns with CWE-269: Improper Privilege Management, specifically illustrating how incorrect assignment of privileges leads to unauthorized access. It also relates closely to CWE-862: Missing Authorization, as the system fails to ensure that the user is authorized for the requested action on the resource. In terms of attack vectors and tactics, this flaw facilitates lateral movement within a compromised environment if an attacker gains initial low-level access through other means or exploits social engineering to get an administrator to assign the capability. It maps to MITRE ATT&CK techniques such as T1078: Valid Accounts, where legitimate credentials are used with excessive privileges, and potentially T1530: Data from Cloud Storage if form submissions are stored externally. The exploitation does not require complex code execution or remote command injection but relies on simple HTTP requests against the REST API endpoints once the privilege escalation condition is met.
Mitigation strategies must focus on both immediate remediation and long-term security hygiene. The primary and most effective solution is to upgrade the Ninja Forms plugin to version 3.15.2 or later, where this authorization logic has been corrected to properly restrict access based on standard WordPress administrative roles rather than broad custom capabilities. For sites that cannot immediately update due to compatibility concerns, administrators should audit user roles and remove any assignments of the specific high-privilege capability associated with form management unless absolutely necessary. Implementing a Web Application Firewall (WAF) can provide an additional layer of defense by monitoring REST API traffic for anomalous patterns indicative of privilege escalation attempts. Furthermore, enforcing strict principle of least privilege across all WordPress installations ensures that delegated access is scoped narrowly to only the functions required for specific tasks, reducing the blast radius if such vulnerabilities are present in other plugins or core components. Regular security audits and penetration testing should be conducted to identify similar misconfigurations where custom capabilities might inadvertently grant excessive permissions.