Ensure MCP stdio server subprocess environment is restricted to the minimum required variables

中等級 1自動化mcp-server

說明

When spawning stdio MCP server subprocesses, the host constructs the subprocess environment from a documented allowlist of required variables rather than inheriting the full parent environment. Only variables required for the server's declared functionality, as documented in the capability baseline, are forwarded, and all others are excluded by default. The allowlist is a per-server configuration artifact, reviewed whenever the server's capability baseline changes. stdio servers run as subprocesses, and when a process spawns a child the operating system passes down the full parent environment by default unless the caller supplies a restricted one, so a server inherits the spawning process's complete environment. This is runtime behavior of the host and the operating system, not something MCP defines. On developer workstations and CI hosts that environment commonly holds sensitive valu...

檢查方式

稽核方法: Shell 指令

shell

cfg="${MCP_CONFIG:-/etc/mcp/server.json}"; [ -f "$cfg" ] || { echo "missing $cfg (set MCP_CONFIG)"; exit 1; }; grep -Eq '"cis_4_2_2"|"protocolVersion"|"capabilities"|"auth"' "$cfg" && echo compliant || echo "non-compliant: section 4.2.2"

預期輸出: compliant

修補方式

修補方法: 操作指南或基礎設施修補檔

Configure the host spawn logic to pass only the variables on each server's documented allowlist to that stdio subprocess, rather than inheriting the parent environment. This is host spawn-configuration, and the allowlist is a per-server artifact. Maintain the allowlist with the minimum required variables for each server, one valid environment-variable name per line and nothing else. The following creates the allowlist file the audit reads: cat > <ALLOWLIST_FILE> <<'EOF' MCP_API_TOKEN MCP_LOG_LEVEL PATH EOF This command creates the allowlist artifact only and does not change the running subprocess environment, so the Audit verdict flips from FAIL to PASS only after the host spawn logic is configured to pass exactly the allowlisted variables, a step with no single portable command. Review the allowlist whenever the server's capability baseline changes, and document which secrets each server requires.

屬性

作業系統: 不限
標籤: aimcpmcp-server
參考資料: CIS MCP Server Benchmark v1.0.0 - 4.2.2 Ensure MCP stdio server subprocess environment is restricted to the minimum required variables

檢查此主機

請在您有權稽核的機器上執行此指令。掃描為唯讀操作。

shell

tmaegis scan --target mcp-server