Path Traversal in Haris-Musa Excel-Mcp-Server
CVE-2026-40576
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 class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.4 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H.
EPSS exploit prediction
EPSS: 0.006 (48.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 48.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.006 · change: +0.003
Affected products
- Haris-Musa Excel-Mcp-Server — versions < 0.1.8
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-40576?
- CVE-2026-40576 is a critical-severity vulnerability in Haris-Musa Excel-Mcp-Server, classified under Path Traversal. CVSS score: 9.4/10. Published 2026-04-21.
- How severe is CVE-2026-40576?
- Critical severity. CVSS v3 base score is 9.4 out of 10.