CVE-2023-45819 in TinyMCE
Summary
by MITRE • 10/25/2023
TinyMCE is an open source rich text editor. A cross-site scripting (XSS) vulnerability was discovered in TinyMCE’s Notification Manager API. The vulnerability exploits TinyMCE's unfiltered notification system, which is used in error handling. The conditions for this exploit requires carefully crafted malicious content to have been inserted into the editor and a notification to have been triggered. When a notification was opened, the HTML within the text argument was displayed unfiltered in the notification. The vulnerability allowed arbitrary JavaScript execution when an notification presented in the TinyMCE UI for the current user. This issue could also be exploited by any integration which uses a TinyMCE notification to display unfiltered HTML content. This vulnerability has been patched in TinyMCE 5.10.8 and TinyMCE 6.7.1 by ensuring that the HTML displayed in the notification is sanitized, preventing the exploit. Users are advised to upgrade. There are no known workarounds for this vulnerability.
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Analysis
by VulDB Data Team • 10/25/2023
The vulnerability identified as CVE-2023-45819 represents a critical cross-site scripting flaw within TinyMCE's Notification Manager API, exposing organizations to significant security risks through client-side code execution. TinyMCE, as a widely adopted open source rich text editor, serves as a foundational component in countless web applications where user-generated content is processed and displayed. This particular vulnerability resides in the notification system designed for error handling, creating a dangerous attack surface where malicious actors can inject harmful HTML content that subsequently executes within the browser context of unsuspecting users.
The technical exploitation of this vulnerability requires specific conditions to be met, including the deliberate insertion of crafted malicious content into the TinyMCE editor followed by the triggering of a notification event. When a notification is displayed, the system fails to sanitize the HTML content passed through the text argument, allowing raw HTML to be rendered directly within the TinyMCE user interface. This unfiltered rendering creates an ideal environment for JavaScript execution, enabling attackers to perform actions such as stealing session cookies, redirecting users to malicious sites, or performing unauthorized operations within the application context. The vulnerability specifically maps to CWE-79, which defines Cross-Site Scripting flaws where untrusted data is improperly integrated into web pages without proper validation or sanitization.
The operational impact of this vulnerability extends beyond simple script execution, as it can compromise entire user sessions and enable persistent attacks through the integration of TinyMCE across various web platforms. Any application utilizing TinyMCE's notification system for displaying error messages, success alerts, or informational content becomes vulnerable to this attack vector, creating a wide attack surface that affects organizations using this component in content management systems, web applications, and collaborative platforms. The vulnerability's exploitation does not require authentication or specialized privileges, making it particularly dangerous as it can be leveraged by attackers with minimal access requirements.
The remediation implemented in TinyMCE versions 5.10.8 and 6.7.1 addresses the root cause by introducing proper HTML sanitization within the notification system, ensuring that any content passed to notifications undergoes rigorous filtering before display. This approach aligns with industry best practices for XSS prevention and follows the ATT&CK framework's mitigation strategies for web application vulnerabilities. Organizations must prioritize upgrading their TinyMCE installations to these patched versions as immediate remediation, as no viable workarounds exist for this vulnerability. The fix demonstrates proper security engineering principles by implementing defense-in-depth measures that prevent malicious content from being executed while maintaining the functionality of the notification system for legitimate use cases.