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| Package Name | Ecosystem | Vulnerable Versions | First Patched Version |
|---|---|---|---|
| @jshookmcp/jshook | npm | = 0.3.1 | 0.3.2 |
Miggo AIRoot Cause AnalysisThe vulnerability, identified as GHSA-c5r6-m4mr-8q5j, is a Server-Side Request Forgery (SSRF) in the '@jshookmcp/jshook' package. The core of the issue lies in the network_icmp_probe and network_traceroute tools. The handlers for these tools, RawLatencyHandlers.handleNetworkIcmpProbe and RawLatencyHandlers.handleNetworkTraceroute, used an insecure helper function, resolveHostname, to resolve the target address provided by the user.
The resolveHostname function would perform a DNS lookup or accept an IP address directly without validating if the target was a private, reserved, or loopback address. This allowed any user with access to these tools to perform network reconnaissance on the server's internal network, identifying live hosts and mapping network routes.
The patch rectifies this by completely removing the resolveHostname function. Instead, the handleNetworkIcmpProbe and handleNetworkTraceroute functions were updated to use a new, secure helper function, resolveAuthorizedHostTarget. This new function integrates with the existing network authorization policy, ensuring that all target addresses are validated and that probes to private networks are blocked unless explicitly authorized. The patch also includes extensive regression tests to verify that the SSRF vulnerability is closed.
RawLatencyHandlers.handleNetworkIcmpProbesrc/server/domains/network/handlers/raw-latency-handlers.ts
RawLatencyHandlers.handleNetworkTraceroutesrc/server/domains/network/handlers/raw-latency-handlers.ts
Test file path in my local checkout:
tests/server/security/jshookmcp-network-meta-boundary.test.ts
Relevant test body:
it('denied control: RTT path consults the SSRF authorization guard for private targets', async () => {
const handler = new RawHandlers();
state.resolveAuthorizedTransportTarget.mockRejectedValue(new Error('RTT measurement blocked: target resolves to a private or reserved address.'));
await expect(handler.handleNetworkRttMeasure({ url: 'https://10.0.0.1/', probeType: 'tcp' })).rejects.toThrow(/blocked/);
expect(state.resolveAuthorizedTransportTarget).toHaveBeenCalled();
expect(state.icmpProbe).not.toHaveBeenCalled();
});
it('bypass proof: call_tool can drive network_icmp_probe to a private IP without the SSRF authorization guard', async () => {
const raw = new RawHandlers();
const ctx = {
router: { has: vi.fn((name: string) => name === 'network_icmp_probe') },
executeToolWithTracking: vi.fn((name: string, args: Record<string, unknown>) => raw.handleNetworkIcmpProbe(args)),
} as any;
const response = await handleCallTool(ctx, { name: 'network_icmp_probe', args: { target: '10.0.0.1', ttl: 64 } });
const body = JSON.parse(response.content[0].text);
expect(body.success).toBe(true);
expect(ctx.router.has).toHaveBeenCalledWith('network_icmp_probe');
expect(ctx.executeToolWithTracking).toHaveBeenCalledWith('network_icmp_probe', { target: '10.0.0.1', ttl: 64 });
expect(state.resolveAuthorizedTransportTarget).not.toHaveBeenCalled();
expect(state.icmpProbe).toHaveBeenCalledWith(expect.objectContaining({ target: '10.0.0.1', ttl: 64 }));
});
Command run:
corepack pnpm exec vitest run --config vitest.config.ts tests/server/security/jshookmcp-network-meta-boundary.test.ts --reporter=verbose
Result:
Test Files 1 passed (1)
Tests 4 passed (4)
The observed vulnerable call sequence is:
call_tool(name=network_icmp_probe, args={target: 10.0.0.1, ttl: 64})
-> ctx.router.has(network_icmp_probe) == true
-> ctx.executeToolWithTracking(network_icmp_probe, validatedArgs)
-> RawHandlers.handleNetworkIcmpProbe(validatedArgs)
-> resolveHostname(10.0.0.1) returns 10.0.0.1
-> icmpProbe({ target: 10.0.0.1, ttl: 64, ... })
resolveAuthorizedTransportTarget is not called on this path. The same missing policy pattern exists for network_traceroute.
An MCP client with access to the active network domain can use the server as a backend-origin internal network probing oracle. The result can reveal whether internal hosts respond, approximate latency, traceroute hops, and ICMP error classes from the server network position.
The practical impact is strongest when jshookmcp is exposed over Streamable HTTP or another remote transport, multiple clients share one server, or the server runs on Windows or with raw socket capability. This is not code execution and does not by itself exfiltrate response bodies.
Apply the same authorization model used by network_rtt_measure and network_latency_stats to network_icmp_probe and network_traceroute. In particular, accept an optional authorization object, resolve the target through the central policy helper or an equivalent host-only policy helper, block private and reserved ranges by default, and pass only the policy-approved resolved address to the native probe. Add regression tests for default-denied private targets, authorized private CIDR access, private hostnames, and call_tool dispatch.
resolveHostnamesrc/server/domains/network/handlers/raw-latency-handlers.ts