DeepChat is an open-source artificial intelligence agent platform that unifies models, tools, and agents. Prior to version 0.5.3, a security vulnerability exists in the Mermaid diagram rendering component that allows arbitrary JavaScript execution. Due to the exposure of the Electron IPC renderer to the DOM, this Cross-Site Scripting (XSS) flaw escalates to full Remote Code Execution (RCE), allowing an attacker to execute arbitrary system commands. Two concurrent issues, unsafe Mermaid configuration and an exposed IPC interface, cause this issue. Version 0.5.3 contains a patch.