Agentic-Flow: OS Command Injection in agentic-flow MCP server tools via unsanitized tool-parameter interpolation into execSync

Summary

agentic-flow versions <= 2.0.13 MCP server tools interpolated attacker-influenceable tool parameters (e.g. agent, task, name, language, agentdb arguments) directly into shell command strings passed to execSync(). A malicious value reaching any of the affected MCP tools could break out of the surrounding double-quoted argument and execute arbitrary OS commands with the privileges of the user running the MCP server.

This was a partial-fix gap: prior commit 6a06854 (#158) fixed CWE-78 elsewhere in the project but missed the MCP server files entirely.

Impact

Any MCP tool argument that the AI agent treats as data but the implementation interpolates into a shell command string becomes a command-injection vector. In MCP deployments where untrusted content (web pages, files, third-party tool output) is processed by the agent, this is reachable without direct attacker access to the host. The HTTP/SSE transports (http-sse.ts, http-streaming-updated.ts) expose the same sinks without authentication or Origin/Host validation, which may raise the effective severity in any deployment that binds them to a reachable network interface.

Affected components

• src/mcp/standalone-stdio.ts — agentic_flow_agent, agentic_flow_create_agent, agentic_flow_list_all_agents, agentic_flow_agent_info, agentic_flow_check_conflicts, agentic_flow_optimize_model, agentic_flow_list_agents, agent_booster_edit_file, agent_booster_batch_edit, agent_booster_parse_markdown, agentdb_stats, agentdb_pattern_store, agentdb_pattern_search, agentdb_pattern_stats
• src/mcp/fastmcp/servers/claude-flow-sdk.ts
• src/mcp/fastmcp/servers/stdio-full.ts
• src/mcp/fastmcp/servers/http-streaming-updated.ts
• src/mcp/fastmcp/servers/http-sse.ts
• src/mcp/fastmcp/servers/poc-stdio.ts
• src/mcp/fastmcp/tools/agent/{execute,list,parallel}.ts
• src/mcp/fastmcp/tools/swarm/orchestrate.ts
• src/mcp/fastmcp/tools/hooks/pretrain.ts (depth path only)

Proof of Concept

// Pre-fix (standalone-stdio.ts, agentic_flow_agent)
let cmd = `npx --yes agentic-flow --agent "${agent}" --task "${task}"`;
const result = execSync(cmd, { encoding: 'utf-8', ... });

Invoking the MCP tool with:

{
  "agent": "coder",
  "task": "x\"; touch /tmp/INJECTED; id > /tmp/rce.txt; echo \""
}

produces, after interpolation:

npx --yes agentic-flow --agent "coder" --task "x"; touch /tmp/INJECTED; id > /tmp/rce.txt; echo ""

When execSync hands that to /bin/sh -c, the shell parses three commands: the truncated npx, then touch /tmp/INJECTED, then id > /tmp/rce.txt; echo "". The marker file /tmp/INJECTED is created and the user's id output is written to /tmp/rce.txt.

Patches

Fixed in [email protected] — every affected call site rewritten to use execFileSync(file, argv, { shell: false }) so attacker-controlled argv elements are passed straight to execve(2) without shell parsing.

Fix PR: ruvnet/agentic-flow#170 (merged at 0c2ec96)

A regression test (tests/security/cwe-78-mcp-execsync.test.ts) was added that statically scans every src/mcp/**/*.ts file and fails the build if any new execSync() call is reintroduced outside of a documented exemption, plus a behavioural smoke check that the canonical PoC payload remains inert when passed as an argv element to execFileSync.

Workarounds

Upgrade to agentic-flow >= 2.0.14. There is no in-product configuration that mitigates this without upgrading.

Downstream pin

The ruflo / claude-flow / @claude-flow/cli packages bumped from 3.12.3 → 3.12.4 to pull the patched agentic-flow:

• [email protected]
• [email protected]
• @claude-flow/[email protected]

End users running any of npx ruflo@latest, npx claude-flow@latest, or npx @claude-flow/cli@latest are pinned to the fixed version.

Credit

Reported by hackchang via a well-scoped red-team report package (npm_agentic-flow_report_package_20260618_163017.zip) that included a sink inventory, a minimized PoC payload, and a clear explanation of why this was a partial-fix gap rather than intended behaviour. The sink inventory directly drove the single-grep pass that closed every reachable call site; the PoC payload became the behavioural smoke test that proves the canonical attack stays inert as an argv element.