CVE-2026-110378 in Ninja Forms Signature Contract Add-On Plugin
Summary
by MITRE • 10/15/2026
Missing Authorization vulnerability in WP E-Signature Ninja Forms Signature Contract Add-On ninja-signature-contract-forms-add-on allows Exploiting Incorrectly Configured Access Control Security Levels.This issue affects Ninja Forms Signature Contract Add-On: from n/a through 3.2.5.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in the WP E-Signature Ninja Forms Signature Contract Add-On, specifically within versions ranging from initial releases up to version 3.2.5, represents a critical failure in access control mechanisms that allows unauthorized actors to perform actions without proper authentication or authorization checks. This flaw is categorized under CWE-862, which denotes Missing Authorization, and aligns with the MITRE ATT&CK technique T1078, Valid Accounts, as it enables attackers to leverage existing system structures to bypass intended security boundaries. The core technical issue stems from an incorrectly configured access control level where the application fails to verify whether the current user has the requisite permissions to execute specific functions related to signature contracts and form submissions. Consequently, any individual with network connectivity to the WordPress instance can interact with sensitive endpoints or API calls associated with the plugin without being validated against a proper permission matrix.
From an operational perspective, this vulnerability exposes significant risks regarding data integrity and confidentiality within digital contract workflows. Since the add-on is designed to handle legally binding electronic signatures and contractual documents, the ability for unauthorized users to manipulate these processes can lead to severe legal and financial repercussions. Attackers could potentially forge signatures, alter contract terms before submission, or access confidential client information embedded in signature requests. The lack of server-side validation means that even if a user is not logged into the WordPress dashboard, they may still be able to submit forms, view pending contracts, or modify existing records by directly manipulating HTTP requests sent to the vulnerable endpoints. This undermines the fundamental trust model required for e-signature platforms, where non-repudiation and authentication are paramount.
The exploitation of this flaw typically involves crafting custom HTTP requests that target specific action handlers within the plugin's codebase while omitting or spoofing necessary authorization tokens or session cookies. Because the vulnerability exists in versions up to 3.2.5, any organization relying on these older iterations for their digital signature needs is at immediate risk. The impact extends beyond simple data leakage; it compromises the legal validity of documents processed through the platform. If an attacker can inject malicious content into a contract or alter the signatory information without detection, the resulting agreements may be deemed invalid in court due to tampering. Furthermore, this vulnerability could serve as an entry point for further attacks, such as cross-site scripting if user input is not properly sanitized after being processed through these unauthenticated channels, thereby expanding the attack surface beyond mere access control failures.
To mitigate this risk, immediate action must be taken by administrators of WordPress sites utilizing the Ninja Forms Signature Contract Add-On. The primary remediation step is to upgrade the plugin to a version later than 3.2.5, where developers have presumably implemented robust server-side authorization checks and validated user permissions before processing any sensitive operations. Until an update can be applied, temporary mitigations include restricting access to the WordPress admin area through IP whitelisting if possible, although this is less effective for front-end form submissions which may not require login depending on configuration. Additionally, implementing a Web Application Firewall with rules specifically targeting suspicious patterns in requests to signature-related endpoints can help block exploitation attempts by detecting anomalous behavior or missing authentication headers. Regular security audits and penetration testing should also be conducted to ensure that no other similar access control flaws exist within the broader application ecosystem, ensuring comprehensive protection against unauthorized manipulation of digital contracts.