GHSA-vwxw-jrg6-9jxv

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GHSA-vwxw-jrg6-9jxv

Summary: MCP Toolbox HTTP tool path parameters allow traversal to unintended endpoints

Details: A path traversal vulnerability exists in the HTTP tool URL builder of googleapis/mcp-toolbox. When constructing downstream API requests, the URL builder substitutes user-controlled pathParams into the configured tool path and parses the resulting string as a relative URL. While it checks that the input does not alter the scheme, host, or user info, it relies on ResolveReference for the final URL resolution. Because dot segments (../) are normalized during this resolution step, an attacker can supply path parameters containing directory traversal sequences to escape the operator-configured path scope. This allows the client to coerce the toolbox into making requests to unintended endpoints on the same target host while forwarding the toolbox's configured credentials (e.g., bypassing a restricted path like /api/v1/users/{{.id}} to reach /admin/secrets).

References: https://nvd.nist.gov/vuln/detail/CVE-2026-11720, https://github.com/googleapis/mcp-toolbox/pull/3218, https://github.com/googleapis/mcp-toolbox/commit/80a66021205e032a424fff87b3dc6d92da58aa77, https://github.com/googleapis/mcp-toolbox, https://github.com/googleapis/mcp-toolbox/releases/tag/v1.3.0