Overview
This article provides a detailed analysis of CVE-2025-64443, a DNS rebinding vulnerability found in MCP Gateway versions 0.27.0 and earlier. MCP Gateway is designed to allow easy and secure running and deployment of MCP servers. This vulnerability can be exploited when MCP Gateway is running in SSE or streaming transport mode, potentially allowing attackers to manipulate MCP servers behind the gateway. It’s crucial to understand the risks and take necessary steps to mitigate this vulnerability.
Technical Details
CVE-2025-64443 stems from a DNS rebinding flaw within MCP Gateway’s SSE and streaming transport modes. When configured to use these modes, MCP Gateway listens on network ports, making it susceptible to DNS rebinding attacks. An attacker can leverage this by hosting a malicious website or serving a malicious advertisement to a victim. When the victim visits the attacker’s content, the attacker can trick the victim’s browser into making requests to the internal IP address where the MCP server is running behind the gateway.
This allows the attacker to bypass same-origin policy restrictions and potentially interact with the MCP server, manipulating tools, and accessing other features exposed by the server. The default `stdio` mode is not affected as it does not listen on network ports.
CVSS Analysis
Currently, the CVSS score and severity rating for CVE-2025-64443 are listed as N/A. This may be due to the vulnerability being recently disclosed or undergoing further analysis. However, the potential impact of DNS rebinding should not be underestimated, as it can lead to significant compromise depending on the functionality of the MCP servers being protected.
Possible Impact
The successful exploitation of CVE-2025-64443 can have serious consequences. An attacker could potentially:
- Manipulate tools and functionalities exposed by the MCP server.
- Access sensitive data managed by the MCP server.
- Compromise the security of other systems connected to the MCP server.
- Gain unauthorized control over MCP server deployments.
The severity of the impact depends heavily on the specific configurations and privileges associated with the MCP servers behind the gateway.
Mitigation and Patch Steps
The recommended mitigation is to upgrade to MCP Gateway version 0.28.0 or later. This version contains a fix that addresses the DNS rebinding vulnerability.
Alternatively, if upgrading is not immediately feasible, consider running MCP Gateway in the default `stdio` mode, which is not vulnerable to this attack. However, this might impact the functionality required in your specific deployment.
To upgrade, follow the official MCP Gateway upgrade instructions available on the Docker Hub or the MCP Gateway GitHub repository.
