CVE-2026-7600 Overview
CVE-2026-7600 is an operating system command injection vulnerability in ArtMin96 yii2-mcp-server version 1.0.2. The flaw resides in the yii_command_help and yii_execute_command functions within src/index.ts of the Model Context Protocol (MCP) Interface component. Attackers can manipulate input passed to these functions to execute arbitrary operating system commands on the host running the MCP server. The attack is exploitable remotely and requires only low privileges. A public exploit has been disclosed, and the project maintainer was notified through an issue report but has not responded. The weakness is classified under CWE-77.
Critical Impact
Remote attackers with low privileges can inject arbitrary OS commands through the MCP interface, leading to unauthorized command execution on systems running yii2-mcp-server 1.0.2.
Affected Products
- ArtMin96 yii2-mcp-server 1.0.2
- Component: MCP Interface (src/index.ts)
- Functions: yii_command_help and yii_execute_command
Discovery Timeline
- 2026-05-02 - CVE-2026-7600 published to NVD
- 2026-05-05 - Last updated in NVD database
Technical Details for CVE-2026-7600
Vulnerability Analysis
The vulnerability is an OS command injection flaw introduced by unsafe handling of user-controlled input within the MCP server interface. The yii_command_help and yii_execute_command functions in src/index.ts pass attacker-influenced data into shell command construction without sufficient sanitization or argument separation. An authenticated remote actor can manipulate the parameters consumed by these functions to append shell metacharacters and execute additional commands in the context of the Node.js process hosting the MCP server. Because MCP servers commonly act as bridges between AI tooling and underlying systems, command injection at this layer can pivot LLM-driven workflows into direct host compromise.
Root Cause
The root cause is improper neutralization of special elements used in an OS command [CWE-77]. The handler functions concatenate or interpolate inputs into a shell invocation rather than executing the binary with strictly enumerated arguments. Shell metacharacters such as ;, &&, |, and backticks are not stripped or escaped, allowing attackers to break out of the intended yii command context.
Attack Vector
The attack vector is network-based. An attacker who can reach the MCP interface and possesses low-level privileges submits a crafted command parameter to the yii_execute_command or yii_command_help tool. The injected payload is appended to the underlying shell invocation, executing attacker-supplied commands with the privileges of the MCP server process. A public exploit issue has been published in the GitHub Public Exploit Issue tracker.
No verified proof-of-concept code is reproduced here. Refer to the VulDB Vulnerability Report and the GitHub Issue Tracker for technical specifics on payload construction.
Detection Methods for CVE-2026-7600
Indicators of Compromise
- Unexpected child processes spawned by the Node.js process running yii2-mcp-server, particularly shells such as /bin/sh, /bin/bash, or cmd.exe.
- MCP request logs containing shell metacharacters (;, &&, ||, |, backticks, $()) within parameters consumed by yii_command_help or yii_execute_command.
- Outbound network connections originating from the MCP server host to unfamiliar destinations following tool invocations.
Detection Strategies
- Monitor process ancestry for shell processes whose parent is the Node.js runtime hosting yii2-mcp-server.
- Inspect MCP transport logs for tool calls referencing yii_execute_command or yii_command_help with payloads containing command separators.
- Apply file integrity monitoring to src/index.ts and adjacent MCP handler files to detect unauthorized modification.
Monitoring Recommendations
- Enable verbose logging on the MCP server and forward events to a centralized logging or SIEM platform for correlation.
- Alert on any execution of system utilities such as curl, wget, nc, whoami, or id initiated by the MCP server process.
- Track authentication events on the MCP interface and correlate low-privilege sessions with subsequent command tool usage.
How to Mitigate CVE-2026-7600
Immediate Actions Required
- Restrict network exposure of the yii2-mcp-server interface to trusted hosts and authenticated users only.
- Disable or remove the yii_command_help and yii_execute_command tools if they are not required for production use.
- Audit existing deployments for signs of exploitation, focusing on the MCP server process tree and recent shell activity.
Patch Information
No official patch is available at the time of publication. According to the advisory, the project was notified through an issue report but has not responded. Track the GitHub Project Repository for upstream fixes.
Workarounds
- Run the MCP server under a dedicated, unprivileged service account with no write access to sensitive files.
- Place the MCP interface behind a reverse proxy that enforces strict input validation and rejects requests containing shell metacharacters.
- Apply OS-level controls such as AppArmor, SELinux, or seccomp profiles to restrict which binaries the Node.js process may execute.
- Consider replacing affected functions locally with implementations that invoke the yii binary using parameterized argument arrays rather than shell strings.
# Example: restrict the service via systemd hardening
[Service]
User=mcpsvc
Group=mcpsvc
NoNewPrivileges=true
ProtectSystem=strict
ProtectHome=true
PrivateTmp=true
RestrictSUIDSGID=true
SystemCallFilter=@system-service
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
