CVE-2023-6635 in Gutenberg Block Editor Toolkit Plugin
Summary
by MITRE • 02/06/2024
The EditorsKit plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation on the 'import_styles' function in versions up to, and including, 1.40.3. This makes it possible for authenticated attackers with administrator-level capabilities or above, to upload arbitrary files on the affected site's server which may make remote code execution possible.
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Analysis
by VulDB Data Team • 04/11/2026
The CVE-2023-6635 vulnerability resides within the EditorsKit plugin for WordPress, a widely used tool designed to enhance content creation capabilities for WordPress administrators. This particular flaw represents a critical security weakness that has persisted through versions up to and including 1.40.3, affecting numerous WordPress installations that rely on this plugin for enhanced editing functionality. The vulnerability specifically targets the 'import_styles' function, which serves as a critical entry point for file handling operations within the plugin's architecture.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the plugin's file upload functionality. The 'import_styles' function fails to properly validate file types before processing uploaded content, creating a pathway for malicious actors to bypass standard security controls. This missing validation allows attackers to upload files with potentially dangerous extensions or content, effectively turning the legitimate file upload feature into a vector for malicious activity. The vulnerability is particularly concerning because it requires only authenticated access at the administrator level or higher, making it accessible to users who already possess elevated privileges within the WordPress environment.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads, as it creates a potential pathway for remote code execution on affected servers. When attackers successfully exploit this vulnerability, they can upload malicious files such as php scripts, web shells, or other executable content that can be triggered through the web server. This capability transforms what might initially appear as a file upload vulnerability into a full remote code execution threat, enabling attackers to gain complete control over the compromised WordPress installation. The implications are severe as this allows for data exfiltration, system compromise, and potential lateral movement within network environments where the WordPress site resides.
This vulnerability aligns with CWE-434, which specifically addresses "Unrestricted Upload of File with Dangerous Type," a well-documented weakness in web application security. The ATT&CK framework categorizes this issue under T1190 - Exploit Public-Facing Application, as it represents an attack vector that leverages publicly accessible plugin functionality. Additionally, the vulnerability demonstrates characteristics of T1059 - Command and Scripting Interpreter, since successful exploitation could enable attackers to execute arbitrary commands on the compromised system. Organizations affected by this vulnerability face significant risk of complete system compromise, particularly when the WordPress installation operates with elevated privileges or when the server environment lacks proper security hardening measures.
The recommended mitigations for CVE-2023-6635 involve immediate action to upgrade the EditorsKit plugin to a version that addresses the file validation issue. Administrators should also implement additional security measures including restricting file upload capabilities, implementing proper file type validation at multiple layers, and conducting thorough security audits of all plugin installations. Network segmentation and monitoring solutions should be deployed to detect unusual file upload activities, while regular security assessments should be performed to identify similar vulnerabilities in other plugins or components. The vulnerability underscores the critical importance of maintaining up-to-date software and implementing defense-in-depth strategies to protect against such exploitation vectors.