CVE-2026-79749: CWE-918: Server-Side Request Forgery (SSRF) in samanhappy mcphub

MCPHub's SSRF protection mechanism in src/utils/ssrf.ts uses a custom function to block certain IPv6 addresses such as loopback, link-local, unique-local, IPv4-mapped, and IPv4-compatible IPv6 addresses. However, it fails to check IPv6 transition address families including NAT64 (64:ff9b::/96), 6to4 (2002::/16), and Teredo (2001::/32). An attacker able to specify a URL for an MCP server connection can exploit this by encoding a private IPv4 address inside these IPv6 transition addresses, bypassing the SSRF guard and potentially reaching internal network resources. This vulnerability is tracked as CWE-918 and has a CVSS 4.0 score of 7.6 (high severity). The vulnerability was fixed in version 1.0.32.

An attacker with the ability to specify URLs for MCP server connections can bypass SSRF protections to access internal infrastructure by exploiting unblocked IPv6 transition address families. This could lead to unauthorized internal network access and potential data exposure or further attacks within the internal environment. There are no known exploits in the wild as of the published date.

The vulnerability has been patched in samanhappy mcphub version 1.0.32. Users should upgrade to version 1.0.32 or later to remediate this issue. Patch status is not explicitly confirmed in vendor advisories but the description states the issue is fixed in version 1.0.32. Until upgraded, users should restrict the ability to specify arbitrary URLs for MCP server connections if possible.