HTB DevHub Complete Writeup - CVE-2026-23744 MCPJam RCE, JupyterLab WebSocket Code Execution & OPSMCP Admin Tool Abuse
DevHub is a HackTheBox Season 11 Medium Linux machine built around a developer tooling stack running entirely on localhost. The attack chain starts with CVE-2026-23744, an unauthenticated RCE in MCPJam Inspector <= 1.4.2 where crafted HTTP requests trigger MCP server installation and arbitrary command execution. From the initial shell, internal enumeration reveals a JupyterLab instance running as analyst with its auth token exposed in process arguments, exploitable via the Jupyter REST API and WebSocket kernel protocol without any browser interaction. Source code of the OPSMCP Flask API running as root contains a hardcoded API key and a hidden admin tool named ops._admin_dump. Calling this tool with the target ssh_keys argument returns root's OpenSSH private key, completing the chain from unauthenticated network access to full root.
May 31, 2026