HTB Kobold Complete Writeup - CVE-2026-23744 MCP Inspector RCE & Docker Escape
Kobold is an Easy-difficulty HackTheBox machine from Season 10 built around modern AI tooling infrastructure. The attack chain begins with subdomain enumeration uncovering an MCPJam Inspector instance vulnerable to CVE-2026-23744 - a critical unauthenticated RCE in the /api/mcp/connect endpoint that allows arbitrary command execution via a crafted serverConfig payload. This delivers a reverse shell as the user ben. Privilege escalation exploits an implicit Docker group membership accessible via newgrp docker, which is leveraged to mount the host filesystem inside a root-running MySQL container and read the root flag directly - a textbook Docker socket escape. This writeup provides a complete step-by-step walkthrough with beginner-friendly explanations of each technique.
Mar 30, 2026