H3-2026-1072¶
MCPJam Inspector Hosted Conformance Server-Side Request Forgery Vulnerability
| Category | VULNERABILITY |
| Base Score | 8.6 |
Description¶
MCPJam Inspector is a hosted conformance testing tool for Model Context Protocol servers. Its hosted conformance endpoints under /api/web/conformance/ perform no validation on the target URL before dialing it. Remote attackers, including guest users, can trigger the conformance runner against internal or cloud metadata addresses such as 169.254.169.254, causing the hosted backend to fetch those addresses on the attacker's behalf. The fetched response, including any error or metadata content, is returned in the conformance evidence output. Exploitation requires only network access to the hosted inspector's conformance API.
Impact¶
Attackers can use the hosted inspector as a proxy to reach cloud instance metadata endpoints. This can expose cloud IAM credentials and internal configuration data. Internal RFC 1918 and link-local services also become reachable through the same channel. Organizations running the hosted MCPJam Inspector backend in a cloud environment face the greatest exposure.