CVE-2026-86801 in To Do List Member Plugin
Summary
by MITRE • 09/17/2026
The To Do List Member WordPress plugin from 1.4 through 1.6 ships a file upload endpoint that does not load WordPress and therefore applies no authentication, capability or nonce check of any kind, and validates only the name of an uploaded file rather than its content, allowing unauthenticated users to store active content served from the site's own origin, and to list and delete the files already staged there.
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Analysis
by VulDB Data Team • 09/17/2026
The vulnerability identified in The To Do List Member WordPress plugin versions 1.4 through 1.6 represents a critical failure in access control and input validation mechanisms within the application architecture. This flaw is rooted in the design of a specific file upload endpoint that operates independently from the standard WordPress execution lifecycle. By not loading the core WordPress framework, the endpoint bypasses all built-in security layers provided by the platform, including authentication checks, capability verification for user roles, and nonce validation to prevent cross-site request forgery attacks. This architectural decision creates an unauthenticated entry point where any external actor can interact with server-side resources without providing valid credentials or proving their identity through standard web application protocols.
From a technical perspective, the core issue lies in the insufficient validation of uploaded files. The plugin only inspects the filename extension and structure but completely neglects to analyze the actual content of the file being uploaded. This allows attackers to bypass common security filters that rely on MIME type detection or magic number verification by uploading malicious scripts disguised with benign extensions or simply relying on the server's default configuration for handling specific file types. Because there are no capability checks, any user, including those who have not logged in, can exploit this endpoint to upload arbitrary files directly into directories accessible via HTTP requests. This effectively turns the web server into a storage medium for attacker-controlled content that is served from the same origin as the legitimate website.
The operational impact of this vulnerability is severe and multifaceted. The primary consequence is remote code execution potential, although it depends heavily on the underlying web server configuration. If the server is configured to execute scripts within the upload directory or if an attacker can chain this with another vulnerability such as a path traversal issue, they could achieve full system compromise. Even without direct code execution, the ability to store active content from the site's own origin facilitates persistent cross-site scripting attacks and phishing campaigns that appear more trustworthy due to their legitimate domain source. Furthermore, the endpoint allows unauthenticated users to list existing files and delete them, which introduces integrity issues and can be used for denial of service by removing critical assets or disrupting application functionality through file manipulation.
This vulnerability aligns with several well-known industry standards and taxonomies that categorize such flaws. It is a classic example of CWE-434, Unrestricted Upload of File with Dangerous Type, as the system fails to restrict the types of files that can be uploaded based on their content or intended use. Additionally, it falls under CWE-286, Improper User Authentication, because the endpoint does not verify the identity of the user making the request before allowing actions like upload, list, and delete operations. In terms of offensive security frameworks, this vulnerability maps to MITRE ATT&CK technique T1505.003, Web Shell: Cloud Accounts or Server-Side Scripting, as it enables the deployment of malicious scripts on a web server that can be used for further exploitation and lateral movement within an organization's network infrastructure.
Mitigation strategies must address both the immediate technical flaw and broader architectural security practices. The most effective remediation is to upgrade the plugin to a version where this vulnerability has been patched, ensuring that all file upload operations are routed through WordPress core functions that enforce authentication and validation checks. If upgrading is not immediately possible, administrators should implement web application firewall rules to block requests targeting the specific vulnerable endpoint or restrict access to any file upload functionality to authenticated users with administrative privileges only. It is also critical to configure the web server to prevent script execution in directories designated for user uploads, thereby neutralizing the impact even if malicious files are successfully uploaded. Regular security audits and code reviews should be conducted to identify similar patterns where custom endpoints bypass standard framework protections, ensuring that all external-facing interfaces adhere to strict input validation and access control policies consistent with secure development lifecycle standards.