CVE-2026-117573 in hagent
Summary
by MITRE • 10/27/2026
hagent through commit 761eec6 contains an OS command injection vulnerability that allows MCP clients to execute shell commands by injecting metacharacters into the args parameter of the hagent_arduino and hagent_esp32 tools. Attackers or prompt-injected agents can supply crafted args interpolated into arduino-cli and idf.py commands run with subprocess.run(shell=True) to execute commands as the MCP server user.
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Analysis
by VulDB Data Team • 10/27/2026
The vulnerability identified in commit 761eec6 of hagent represents a critical OS command injection flaw within the Model Context Protocol client implementation, specifically affecting the arduino-cli and idf.py tool integrations. This security defect arises from the improper handling of input parameters passed to external system commands. The core technical issue lies in the use of subprocess.run with shell=True while directly interpolating user-supplied arguments into the command string without adequate sanitization or validation. When an MCP client provides crafted args containing metacharacters such as semicolons, pipes, ampersands, or backticks, these characters are interpreted by the underlying operating system shell rather than being treated as literal data. This allows an attacker to break out of the intended command context and execute arbitrary system commands with the privileges of the user running the MCP server process.
The operational impact of this vulnerability is severe due to its potential for remote code execution on the host machine hosting the MCP server. An adversary, whether acting directly or through a prompt-injected agent that manipulates the input sent by an LLM, can exploit this flaw to gain unauthorized access to system resources. By injecting shell commands into the args parameter of hagent_arduino and hagent_esp32 tools, attackers can perform actions ranging from data exfiltration and credential theft to installing malware or pivoting to other systems within the network environment. The severity is compounded by the fact that MCP servers often run with elevated privileges relative to standard user applications, increasing the blast radius of a successful exploitation attempt. This vulnerability aligns closely with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection and maps to ATT&CK technique T1059 Command and Scripting Interpreter where attackers leverage system shells for execution.
Mitigation strategies must focus on eliminating the reliance on shell interpretation when executing external programs. The most effective remediation is to refactor the subprocess calls to use a list-based argument format instead of string interpolation, thereby bypassing the shell entirely. By passing arguments as separate elements in an array, the operating system treats each element strictly as data rather than parsing it for special characters. Additionally implementing strict input validation that rejects or escapes any metacharacters not explicitly required by the tool can provide a secondary layer of defense. It is also advisable to apply principle of least privilege by running MCP server processes under restricted user accounts with minimal permissions, limiting the potential damage even if an injection occurs. Regular security audits and static analysis tools should be employed to detect similar patterns in other parts of the codebase where external commands are invoked dynamically based on untrusted input sources.