Horizon Alert
Summary of the vulnerability and why it matters
An issue in excel-mcp-server allows attackers to read, write, or overwrite files on the server. This happens because the server improperly handles file paths, even though it's designed to restrict operations to a specific directory. The default network settings make this vulnerability easy to exploit remotely without authentication.
- Attacker can modify or delete files.
- Attacker can read sensitive files.
- Network access required.
Attack Path
How an attacker could exploit the issue
An unauthenticated attacker on the network could exploit this by sending specially crafted file path arguments to the server, allowing them to read, write, or overwrite arbitrary files on the host. This is possible because the server fails to properly validate absolute and relative paths, and it defaults to listening on all network interfaces without authentication.
- Remote network access needed.
- Target file operations via MCP handlers.
- Server binds to all interfaces by default.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability appears highly weaponizable due to its critical severity and lack of authentication, allowing unauthenticated network attackers to read, write, and overwrite arbitrary files. The default configuration, binding to all interfaces and using network-accessible transport modes, facilitates widespread exploitation without any prior access needed. While the software is intended for internal use, insecure default settings expose it to remote threats.
- No authentication required for exploitation.
- Critical impact on confidentiality, integrity, and availability.
- Defaults to network-accessible configuration.
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
Prioritize immediate patching of excel-mcp-server to version 0.1.8 to address the critical path traversal vulnerability. If patching is not feasible, isolate the affected services from network access to prevent exploitation via the exposed network transport.
- Patch excel-mcp-server to 0.1.8.
- Isolate affected servers from network.
- Monitor for unauthorized file access.
