CVE-2017-9336 in WP Editor.MD Plugin
Summary
by MITRE
The WP Editor.MD plugin 1.6 for WordPress has a stored XSS vulnerability in the content of a post.
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Analysis
by VulDB Data Team • 10/13/2019
The WP Editor.MD plugin version 1.6 for WordPress contains a critical stored cross-site scripting vulnerability that allows attackers to inject malicious scripts into post content. This vulnerability exists within the plugin's handling of user input when processing post content, creating a persistent security risk that affects all WordPress installations using this specific plugin version. The flaw enables unauthorized individuals to execute arbitrary JavaScript code in the browsers of users who view affected posts, making it particularly dangerous due to its stored nature. The vulnerability impacts the integrity and confidentiality of WordPress sites by potentially allowing attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users. This issue represents a significant threat to WordPress ecosystems where the plugin is actively used, as it leverages the trust relationship between users and the content management system. The stored XSS vulnerability specifically allows attackers to inject malicious code that persists in the database and executes whenever users view the affected content, making it more severe than reflected XSS attacks that require specific user interaction.
The technical implementation of this vulnerability stems from inadequate input sanitization and output encoding within the plugin's content processing pipeline. When users create or edit posts using the WP Editor.MD plugin, the system fails to properly validate and escape user-supplied content before storing it in the database. This oversight allows malicious payloads to be stored alongside legitimate content, where they remain dormant until accessed by other users. The vulnerability manifests when the plugin renders post content back to users, executing the stored malicious scripts in their browser context. The flaw specifically affects the plugin's handling of markdown content and HTML rendering functionality, where user input is not properly escaped or filtered before being output to web pages. This represents a classic CWE-79 - Cross-site Scripting vulnerability, where the system fails to validate or sanitize user-provided data before incorporating it into dynamically generated web content.
The operational impact of this vulnerability extends beyond simple script execution, potentially enabling sophisticated attack vectors that compromise entire WordPress installations. Attackers can leverage this vulnerability to steal administrator credentials, modify website content, inject malicious advertisements, or redirect users to phishing sites. The stored nature of the vulnerability means that once exploited, the malicious code persists indefinitely until manually removed, making it particularly dangerous for high-traffic websites where content is frequently viewed by multiple users. This vulnerability also creates opportunities for attackers to establish persistent backdoors or perform privilege escalation attacks, especially if the affected WordPress installation lacks proper security hardening. The impact is amplified when considering that many WordPress sites use the plugin for rich text editing, making the attack surface larger and more likely to be exploited by threat actors targeting content management systems. The vulnerability affects the availability and integrity of website content, potentially leading to complete site compromise and data breaches.
Mitigation strategies for this vulnerability require immediate action including plugin updates to versions that address the XSS flaw, implementing proper input validation and output encoding mechanisms, and conducting thorough security audits of all installed WordPress plugins. Administrators should prioritize updating to the latest plugin version that contains the security fix, while also implementing content security policies to limit the execution of unauthorized scripts. Regular security monitoring and vulnerability scanning should be implemented to detect similar issues in other plugins or themes. The remediation process involves not only updating the vulnerable plugin but also reviewing all stored content for potential malicious scripts and implementing proper sanitization procedures. Organizations should consider implementing web application firewalls and security headers to provide additional protection layers against similar vulnerabilities. This vulnerability highlights the importance of maintaining up-to-date WordPress plugins and following security best practices such as implementing the principle of least privilege and regular security assessments. The remediation efforts should also include staff training on recognizing potential security threats and understanding the risks associated with third-party plugin integration in content management systems.