Langflow: Authenticated RCE via MCP Stdio transport allows any user to execute arbitrary OS commands on the server

Langflow is a tool for building and deploying AI-powered agents and workflows. Prior to 1.9.0, any authenticated Langflow user can achieve Remote Code Execution (RCE) on the server by adding an MCP server with the "Stdio" transport. The user-supplied command field is passed directly to bash -c "exec {command}" with zero validation, no allowlisting, and no sandboxing. The command executes immediately when the server list is fetched. Additionally, the env field allows arbitrary environment variable injection (e.g., LD_PRELOAD, PATH override). This vulnerability is fixed in 1.9.0.

Source published

5 Oct 2026 20:46:18 UTC

Source modified

6 Oct 2026 18:20:28 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H