Vulnerability · Published Aug 13, 2026 · Assigned by GitHub_M
CVE-2026-49856@jshookmcp/jshook: ICMP probe and traceroute skip local-network SSRF authorization
Medium 4.3
In plain English
A medium-severity server-side request forgery in jshookmcp from vmoranv. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
@jshookmcp/jshook is an MCP server that gives AI agents tools for JavaScript analysis and security research. In version 0.3.1, he network domain has a central SSRF authorization policy that blocks private, loopback, link-local, and reserved targets unless an explicit authorization object allows private network access. The policy is enforced by raw HTTP/TCP/TLS RTT tools, but the ICMP probe and traceroute tools resolve the target and invoke the native ICMP/traceroute sink directly. An MCP client with access to an active network domain can therefore ask the jshookmcp server to probe internal addresses even when local SSRF access is disabled for the other raw network tools. This exposes an internal reachability and route mapping primitive from the server network position. Version 0.3.2 fixes the issue.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @jshookmcp/jshook | 0.3.2 | GHSA-c5r6-m4mr-8q5j |
Affected products (as reported)
Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N