fkie_cve-2026-77339

Process Compose is a scheduler and orchestrator for non-containerized applications. Prior to 1.120.0, the MCP SSE listener in src/mcp/server.go accepts browser-origin requests to /sse and the returned message endpoint without validating the Host header, validating the Origin header, or authenticating the caller. When MCP SSE is enabled, a malicious website can use DNS rebinding to reach the loopback listener and issue MCP requests. If expose_control_tools is enabled, the attacker can enumerate process state, read or search logs, truncate logs, and start, stop, restart, or scale local processes; configured user-defined tools can expose additional commands and output. The Gin REST API token middleware does not protect this separately started MCP listener. This issue is fixed in version 1.120.0.

GHSA-5gm3-9crp-6g3v — Process Compose: Browser DNS rebinding lets websites control local process-compose MCP tools

Affected: Go: github.com/f1bonacc1/process-compose

## Summary

A malicious website can use DNS rebinding to control a developer's local process-compose MCP SSE listener when MCP SSE is enabled. The vulnerable path accepts browser-origin requests before any Host validation, Origin validation, or caller-secret check, then dispatches the requests into process-compose MCP tools.

This advisory covers `https://github.com/F1bonacc1/process-compose`, confirmed at commit `d56aa59df04b72f8644811ac581a051bec05e485`.

The issue is in the MCP SSE transport, not the Gin REST API. The REST API token middleware protects REST routes, but the MCP listener is started separately and does not inherit that protection.

## Affected Code

Root cause:

```text src/types/mcp.go:24-30 SSE is the default MCP transport when mcp_server.transport is omitted. src/types/mcp.go:64-70 SSE configuration requires only host and port. There is no auth, Host allowlist, Origin allowlist, or caller-secret field. src/mcp/server.go:203-214 The server starts server.NewSSEServer(s.mcpServer) directly on the configured address. src/api/routes.go:32-39 X-PC-Token-Key middleware is installed on the Gin REST router, not on the MCP SSE listener. ```

Impact surface:

```text src/mcp/mcp_manager.go:33-38 expose_control_tools registers built-in process-compose control tools. src/mcp/control_tools.go:26-116 The registered tools start, stop, restart, scale, read logs, search logs, and truncate logs. src/mcp/control_tools.go:121-142 The registered tools retu…

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fkie_cve-2026-77339

GHSA-5gm3-9crp-6g3v — Process Compose: Browser DNS rebinding lets websites control local process-compose MCP tools