A flaw in MCPHub’s SSRF guard allows an attacker to supply a target URL that contains a disguised IPv4 address encoded inside an IPv6 transition address family (NAT64, 6to4, Teredo). The guard fails to block these transition forms, permitting the application to dereference internal resources that would normally be protected. The vulnerability enables an attacker to initiate requests on behalf of the server, potentially exfiltrating sensitive data or interacting with internal services. It is a classic SSRF weakness identified as CWE-918.

The issue affects versions of the product mcphub from vendor samanhappy prior to 1.0.32. The upstream project released a patch in release 1.0.32 that adds proper checks to the SSRF guard. Any deployment running an earlier version and accepting externally supplied URLs for MCP server connections is impacted.

The CVSS score of 7.6 indicates moderate to high severity, reflecting the potential for internal data exposure and disruption. EPSS information is not provided, so exploitation probability is unknown, but the absence of a KEV listing suggests no publicly known exploits have been reported yet. The likely attack vector is through an external hacker controlling a request that forces MCPHub to connect to an internal endpoint via a crafted URL. Successful exploitation requires the ability to influence the target URL; once achieved the guard is bypassed, giving the attacker a foothold into the internal network.