# CVE-2026-40576: CVE-2026-40576: excel-mcp-server Path Traversal Allows Unauthenticated File Read and Overwrite (CVSS 9.4)

> CVE-2026-40576 is a critical-severity path traversal issue (CVSS 9.4) in excel-mcp-server, a MCP server. Affected: excel-mcp-server <= 0.1.7 (fixed in 0.1.8). Fixed in 0.1.8.

- **Canonical URL:** https://catalog.anomity.ai/vuln/cve-2026-40576
- **Aliases:** ti-060
- **Severity:** critical
- **CVSS:** 9.4
- **Attack type:** Path traversal
- **Component:** excel-mcp-server (MCP server)
- **Exploited in the wild:** no known exploitation
- **Published:** 2026-04-23
- **Last verified:** 2026-11-01
- **JSON:** https://catalog.anomity.ai/api/entries/vuln/cve-2026-40576

## Summary

A path traversal flaw in excel-mcp-server let unauthenticated attackers read, write and overwrite arbitrary files. Its get_excel_path() passed absolute paths through without validation and failed to resolve ../ traversal sequences, and because the server binds to all network interfaces with no authentication by default, remote exploitation was straightforward. This is the recurring shape of MCP server risk: the code flaw is ordinary, but the default deployment posture turns it into remote file write.

## Affected versions

| Affected | Fixed in |
| --- | --- |
| excel-mcp-server <= 0.1.7 (fixed in 0.1.8) | 0.1.8 |

## Am I affected by CVE-2026-40576?

You are affected if you run excel-mcp-server <= 0.1.7 (fixed in 0.1.8). Versions 0.1.8 and later include the fix.

## How do I fix CVE-2026-40576?

Upgrade excel-mcp-server to 0.1.8+. Bind MCP servers to 127.0.0.1 rather than 0.0.0.0, put authentication in front of any MCP server reachable off-host, and run file-handling MCP servers against a scoped or read-only filesystem.

## How do I find every machine running excel-mcp-server?

Anomity inventories the AI agents, MCP servers, IDE extensions and skills on each developer device, so you can see which machines run excel-mcp-server and which version, then enforce a policy on it.

## References

- article: https://www.sentinelone.com/vulnerability-database/cve-2026-40576/
- cve: https://nvd.nist.gov/vuln/detail/CVE-2026-40576

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Source: Anomity Security Database (https://catalog.anomity.ai/vuln). Detect affected AI tools on developer devices: https://anomity.ai/?utm_source=catalog&utm_medium=vuln-md&utm_campaign=cve-2026-40576