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This vulnerability exploits the trust model between a web browser and a network service. When the Docker MCP Gateway is run in SSE or streaming (--transport) mode, it binds a local HTTP server to a network port (e.g., localhost:3000) to communicate with a frontend client. A DNS rebinding attack tricks the victim’s browser into bypassing the Same-Origin Policy. An attacker hosts a malicious website that, when visited, uses JavaScript to make requests to http://localhost:3000`. The initial DNS resolution points to the attacker's server, but the TTL is set to 0 seconds. The browser is then tricked to re-resolve the domain name to127.0.0.1, now allowing the malicious script to directly interact with the locally running MCP Gateway. This grants the attacker's code the same level of access as the local frontend, enabling manipulation of any connected MCP servers and their exposed tools (like shell commands or file operations) within the Docker context.
Platform: Docker MCP Gateway
Version: < v0.28.0
Vulnerability: DNS Rebinding
Severity: High
date: 2025-12-03
<h2 style="color: blue;">Prediction: Patched 2025-12-03</h2>
<h2 style="color: blue;">What Undercode Say:</h2>
Check if vulnerable version is running docker ps | grep mcp-gateway Example of running the gateway in vulnerable mode docker run -p 3000:3000 ghcr.io/docker/mcp-gateway --transport sse Curl command an attacker might script to probe for the service curl -v http://localhost:3000/messages
<h2 style="color: blue;">How Exploit:</h2>
<h2 style="color: blue;">1. Attacker crafts malicious website.</h2>
<h2 style="color: blue;">2. Victim with local gateway visits site.</h2>
<h2 style="color: blue;">3. JavaScript performs DNS rebinding.</h2>
<h2 style="color: blue;">4. Script connects tolocalhost:3000`.
5. Sends MCP protocol messages.
6. Executes commands via compromised servers.
Protection from this CVE:
1. Upgrade to v0.28.0.
2. Use default stdio mode.
3. Avoid SSE/streaming transports.
4. Implement network segmentation.
5. Use firewall rules.
6. Employ CORS restrictions.
Impact:
1. Remote code execution.
2. Tool manipulation.
3. Data exfiltration.
4. Browser-based attack.
5. No user interaction.
6. Full server compromise.
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
