CVE-2025-64443 is a vulnerability in docker's MCP Gateway component, specifically affecting versions 0.27.0 and earlier when operating in sse or streaming transport modes. The root cause is a DNS rebinding attack vector, where an attacker can manipulate the victim's browser to bypass same-origin policies and interact with MCP servers running behind the gateway. MCP Gateway facilitates the deployment and management of MCP servers, which expose various tools and features that can be manipulated if accessed maliciously. The vulnerability arises because the gateway listens on network ports in these modes, making it accessible to browser-based attacks. An attacker can lure a victim to a malicious website or serve a malicious advertisement, triggering the DNS rebinding exploit to gain unauthorized access to internal MCP server functionalities. This can lead to unauthorized manipulation of server tools, potentially impacting the integrity and availability of services. The default stdio mode of MCP Gateway is not vulnerable as it does not listen on network ports, thus not exposed to network-based browser attacks. The issue was addressed and fixed in MCP Gateway version 0.28.0. The CVSS 4.0 vector indicates a network attack vector with low complexity, no privileges required, partial user interaction, and high impact on integrity and availability, but low impact on confidentiality. No known exploits have been reported in the wild as of the publication date. The vulnerability is categorized under CWE-749, which relates to exposed dangerous methods or functions, indicating that the MCP Gateway exposes functionality that should be protected but is accessible due to the DNS rebinding flaw.

For European organizations, the impact of CVE-2025-64443 can be significant, especially those relying on docker MCP Gateway for managing MCP servers in sse or streaming modes. Successful exploitation can allow attackers to manipulate internal MCP server tools and features, potentially disrupting operations, corrupting data, or causing service outages. This undermines the integrity and availability of critical infrastructure or applications managed via MCP servers. Since the attack is browser-based and requires user interaction, phishing or malicious advertising campaigns could be vectors, increasing the risk in environments with high user exposure to the internet. Organizations with sensitive or critical MCP server deployments may face operational disruptions or reputational damage if exploited. The vulnerability does not directly expose confidential data but can indirectly affect confidentiality if attackers manipulate server configurations or access controls. The lack of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as the vulnerability is publicly disclosed. European entities with containerized environments and modern DevOps pipelines using MCP Gateway are particularly at risk if they have not upgraded to the patched version. The complexity of exploitation is low, increasing the likelihood of opportunistic attacks if mitigations are not applied.

The primary and most effective mitigation is to upgrade MCP Gateway to version 0.28.0 or later, where the DNS rebinding vulnerability is fixed. Organizations should audit their MCP Gateway deployments to identify instances running in sse or streaming transport modes and prioritize patching these. If immediate upgrade is not feasible, temporarily switching MCP Gateway to the default stdio mode can mitigate exposure, as it does not listen on network ports and is not vulnerable to this attack. Network-level mitigations include implementing strict Content Security Policies (CSP) and SameSite cookie attributes to reduce the risk of DNS rebinding attacks via browsers. Additionally, organizations should employ network segmentation and firewall rules to restrict access to MCP Gateway ports only to trusted internal networks. User awareness training to recognize phishing and malicious advertisements can reduce the likelihood of user interaction required for exploitation. Monitoring network traffic for unusual connections to MCP Gateway ports and deploying web application firewalls (WAF) with rules targeting DNS rebinding patterns can provide additional defense layers. Regular vulnerability scanning and penetration testing focused on container orchestration components should include checks for this vulnerability.