CVE-2026-5603 Overview
CVE-2026-5603 is an operating system command injection vulnerability in elgentos/magento2-dev-mcp versions up to 1.0.2. The flaw resides in the executeMagerun2Command function within src/index.ts. An authenticated local attacker can manipulate command parameters to inject arbitrary OS commands that execute in the context of the Model Context Protocol (MCP) server process. The issue is tracked under CWE-77: Improper Neutralization of Special Elements used in a Command. A patch is available in commit aa1ffcc0aea1b212c69787391783af27df15ae9d, and proof-of-concept details are public.
Critical Impact
A local attacker with low privileges can inject arbitrary shell commands through the executeMagerun2Command handler, leading to unauthorized command execution within the developer MCP environment.
Affected Products
- elgentos magento2-dev-mcp versions up to and including 1.0.2
- The vulnerable code path is in src/index.ts (executeMagerun2Command function)
- Magento 2 development environments integrating this MCP server
Discovery Timeline
- 2026-04-05 - CVE-2026-5603 published to the National Vulnerability Database (NVD)
- 2026-04-29 - Last updated in NVD database
Technical Details for CVE-2026-5603
Vulnerability Analysis
The magento2-dev-mcp package exposes Magento 2 developer tooling through a Model Context Protocol server. The executeMagerun2Command function constructs and runs magerun2 CLI commands based on incoming MCP tool invocations. Because the function passes attacker-controlled input into a shell context without sufficient sanitization, additional commands can be appended using standard shell metacharacters such as ;, &&, |, or backticks. The injected commands run with the privileges of the user hosting the MCP server, which is typically a developer account with broad access to the local Magento project and credentials.
Root Cause
The root cause is improper neutralization of special elements within a command string built dynamically from external input [CWE-77]. The function trusts the supplied argument values and concatenates them into the command line rather than passing them as a discrete argv array to a non-shell execution primitive. The maintainer addressed the issue in commit aa1ffcc0aea1b212c69787391783af27df15ae9d, which adjusts how arguments are handled before execution. See the GitHub commit details and the associated pull request.
Attack Vector
Exploitation requires local access and low privileges. An attacker who can submit MCP tool requests to the locally running magento2-dev-mcp server, for example through a compromised AI assistant integration or a malicious project file consumed by an MCP client, can craft a parameter value that breaks out of the intended magerun2 invocation. The injected payload is executed by the shell after the legitimate command. Refer to the bug report PDF and the issue tracker entry for reproduction details.
Detection Methods for CVE-2026-5603
Indicators of Compromise
- Unexpected child processes spawned by the Node.js process hosting magento2-dev-mcp, especially shells such as /bin/sh, bash, or cmd.exe.
- magerun2 command lines containing shell metacharacters (;, &&, ||, |, `, $()) in process accounting logs.
- New or modified files in the Magento project directory created by the MCP server process outside of normal developer workflows.
- Outbound network connections from the MCP server process to non-Magento infrastructure.
Detection Strategies
- Monitor process trees rooted at node or the MCP runtime for invocations of magerun2 followed by anomalous shell commands.
- Implement command-line argument logging on developer workstations and CI runners that host the MCP server.
- Compare the installed version of elgentos/magento2-dev-mcp against 1.0.2 and the patched commit hash in software composition analysis (SCA) tooling.
Monitoring Recommendations
- Enable endpoint detection telemetry on developer machines and centralize MCP server logs for review.
- Alert on magerun2 invocations that include redirection operators or process substitution sequences.
- Track Git activity on the MCP server to detect unauthorized changes to project files following suspicious command execution.
How to Mitigate CVE-2026-5603
Immediate Actions Required
- Upgrade elgentos/magento2-dev-mcp to a version that includes commit aa1ffcc0aea1b212c69787391783af27df15ae9d or later.
- Audit recent magerun2 invocations and MCP server logs for evidence of command injection attempts.
- Restrict which MCP clients and AI assistants are permitted to connect to the local server and review their tool-call histories.
Patch Information
The maintainer published the fix in commit aa1ffcc0aea1b212c69787391783af27df15ae9d, merged through pull request #5. Update via your package manager to pull the patched release from the magento2-dev-mcp repository. Vulnerability tracking details are available on the VulDB entry.
Workarounds
- Stop or disable the magento2-dev-mcp server on developer workstations until the patched version is installed.
- Run the MCP server inside an unprivileged container or sandbox that limits access to the host filesystem and credentials.
- Configure MCP clients to require explicit user confirmation before executing executeMagerun2Command tool calls.
- Avoid loading untrusted project workspaces or AI prompts that can drive MCP tool invocations on the developer host.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
