CVE-2026-40576

CriticalCVSS 9.4

Published: 21/04/2026(UTC)Updated: 26/10/2026(UTC)Translated: 26/10/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.47%

40th percentile - higher than 40% of all known CVEs

Summary

excel-mcp-server up to and including 0.1.7 contains a path traversal vulnerability in SSE or Streamable-HTTP transport mode where an unauthenticated attacker can read, write, and overwrite arbitrary files on the host. The get_excel_path() function fails to enforce the EXCEL_FILES_PATH boundary due to two independent flaws. The issue is fixed in 0.1.8.

Risk Assessment

An unauthenticated network attacker can read and overwrite arbitrary files on the host, leading to full system compromise. The default bind to 0.0.0.0 increases exposure.

Recommendation

Upgrade excel-mcp-server to version 0.1.8. Until updated, restrict network access to the service and avoid SSE/Streamable-HTTP mode without authentication.

Other vulnerabilities in excel-mcp-server

CVE-2026-85661Critical
excel-mcp-server 0.1.8 fails to enforce path confinement in stdio mode when EXCEL_FILES_PATH is unset, allowing attackers to read and write arbitrary files. Attackers can supply unchecked file paths to access any file accessible to the process.

Original NVD description (English source)

excel-mcp-server is a Model Context Protocol server for Excel file manipulation. A path traversal vulnerability exists in excel-mcp-server versions up to and including 0.1.7. When running in SSE or Streamable-HTTP transport mode (the documented way to use this server remotely), an unauthenticated attacker on the network can read, write, and overwrite arbitrary files on the host filesystem by supplying crafted filepath arguments to any of the 25 exposed MCP tool handlers. The server is intended to confine file operations to a directory set by the EXCEL_FILES_PATH environment variable. The function responsible for enforcing this boundary — get_excel_path() — fails to do so due to two independent flaws: it passes absolute paths through without any check, and it joins relative paths without resolving or validating the result. Combined with zero authentication on the default network-facing transport and a default bind address of 0.0.0.0 (all interfaces), this allows trivial remote exploitation. This vulnerability is fixed in 0.1.8.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS