CVE-2025-66222 is a critical security vulnerability identified in the DeepChat AI assistant developed by ThinkInAIXYZ, affecting versions earlier than 0.5.0. The root cause is a stored Cross-Site Scripting (XSS) vulnerability within the Mermaid diagram renderer component, which allows an attacker to inject and persist malicious JavaScript code that executes in the context of the DeepChat application. This XSS flaw is particularly dangerous because DeepChat is built on Electron, a framework that combines Chromium and Node.js, exposing an IPC (Inter-Process Communication) bridge. Attackers can leverage this IPC bridge to escalate the XSS to Remote Code Execution (RCE) by registering and launching a malicious Model Context Protocol (MCP) server. This escalation means that an attacker can execute arbitrary code on the host machine running DeepChat, potentially taking full control of the system. The vulnerability does not require prior authentication but does require user interaction, such as viewing or interacting with malicious Mermaid diagrams. The CVSS v3.1 score of 9.7 reflects the critical nature of this vulnerability, with network attack vector, low attack complexity, no privileges required, and user interaction needed. The impact spans confidentiality, integrity, and availability, as attackers can steal sensitive data, manipulate application behavior, or disrupt service. No patches or exploit code are currently publicly available, but the threat is significant given the potential for full system compromise. The vulnerability is classified under CWE-94, indicating improper control of code generation, which is a severe security weakness in software development. Organizations using DeepChat, especially in environments where untrusted content is rendered or shared, are at heightened risk.

For European organizations, the impact of CVE-2025-66222 is substantial. DeepChat users could face complete system compromise if attackers exploit this vulnerability, leading to data breaches, intellectual property theft, and operational disruptions. Sectors such as finance, healthcare, government, and critical infrastructure that increasingly integrate AI assistants like DeepChat into workflows are particularly vulnerable. Confidential information processed or stored by DeepChat could be exposed or manipulated, undermining trust and compliance with regulations such as GDPR. The ability to execute arbitrary code remotely also raises the risk of deploying ransomware or other malware, causing downtime and financial losses. Since the vulnerability requires user interaction, phishing or social engineering campaigns could be used to trick users into triggering the exploit. The lack of known exploits in the wild currently provides a window for proactive defense, but the high severity demands urgent mitigation to prevent potential attacks.

1. Upgrade DeepChat to version 0.5.0 or later as soon as an official patch addressing CVE-2025-66222 is released by ThinkInAIXYZ. 2. Until a patch is available, restrict or disable the rendering of Mermaid diagrams from untrusted or external sources to prevent injection of malicious scripts. 3. Implement strict Content Security Policies (CSP) within the Electron application to limit the execution of inline scripts and restrict IPC communication to trusted endpoints only. 4. Employ application-level sandboxing to isolate the DeepChat process and minimize the impact of potential code execution. 5. Educate users about the risks of interacting with untrusted content and implement phishing awareness training to reduce the likelihood of user interaction exploitation. 6. Monitor network and application logs for unusual IPC activity or attempts to register unauthorized MCP servers. 7. Use endpoint detection and response (EDR) tools to detect anomalous behavior indicative of exploitation attempts. 8. Coordinate with vendors and security teams to ensure timely vulnerability disclosure and patch management.