Microsoft UFO: Arbitrary code execution in `run_shell` via `explorer.exe` argument injection

Microsoft UFO is an open-source framework for intelligent automation across devices and platforms. Prior to 3.0.9, the run_shell tool in the CommandLineExecutor component of ufo/client/mcp/local_servers/cli_mcp_server.py validates only the first token of the bash_command parameter and permits explorer.exe. On Windows, explorer.exe delegates its following path argument to ShellExecute, so an attacker-influenced agent call can launch an arbitrary executable or script as the desktop user even though the subprocess uses shell=False. Exploitation depends on a user running an affected agent workflow and on inducing the tool call, but successful execution can access or modify that user's files, tokens, and sessions. This issue is fixed in version 3.0.9.

Source published

6 Oct 2026 14:09:23 UTC

Source modified

9 Oct 2026 01:01:55 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H