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Path TraversalWeakness · CWE-22

CVE-2026-40576

CRITICAL · 9.4 CVSS v3.1 Published 2026-04-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Path traversal vulnerability in excel-mcp-server's get_excel_path() function allows unauthenticated remote attackers to read/write arbitrary files on the host by supplying crafted absolute or unvalidated relative paths via MCP tool handlers. The function fails to enforce the EXCEL_FILES_PATH boundary restriction due to two flaws: absolute paths pass through unchecked, and relative paths are joined without resolving/validating the result. Combined with zero authentication on default SSE/Streamable-HTTP transports bound to 0.0.0.0, this enables trivial remote exploitation.

MitigationUpgrade excel-mcp-server to version 0.1.8 or later. If immediate upgrade is not possible, ensure the server is not exposed to untrusted networks or implement network-level access controls.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify if excel-mcp-server is running
    Check running processes or container instances for excel-mcp-server. Look for process listings, container logs, or service management tools showing the server active.
    Affected if excel-mcp-server is actively running in the environment
  2. Determine the installed version
    Run the package manager command or CLI tool to retrieve the excel-mcp-server version (e.g., npm list, pip show, or server --version), then compare it to the affected range below version 0.1.8.
    Affected if The installed version is prior to 0.1.8 (any 0.x.y version where y < 8 or where the 0.x series is less than 0.1)
  3. Verify network binding configuration
    Inspect the server startup configuration or runtime settings for the transport binding. Look for bind addresses in config files, environment variables, or command-line arguments.
    Affected if The server is bound to 0.0.0.0 (all interfaces) rather than localhost or a restricted address
  4. Confirm authentication status
    Review the server configuration for authentication settings. Check whether any authentication mechanism (tokens, API keys, OAuth) is enabled in the config files or environment.
    Affected if No authentication is configured or authentication is explicitly disabled (default un-authenticated state)
  5. Inspect EXCEL_FILES_PATH setting
    Locate the EXCEL_FILES_PATH configuration in config files, environment variables, or runtime settings. Verify whether it is set and what directory it points to.
    Affected if EXCEL_FILES_PATH is configured and the server accepts file path inputs without additional validation layers

The environment is likely affected if excel-mcp-server version is below 0.1.8, the service is exposed on 0.0.0.0, and authentication is not enforced, allowing unauthenticated path traversal attacks.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade excel-mcp-server to version 0.1.8 or later. If immediate upgrade is not possible, ensure the server is not exposed to untrusted networks or implement network-level access controls.

Recommended fix High confidence

0.1.8

  1. Check the currently installed version of excel-mcp-server
  2. Upgrade excel-mcp-server to version 0.1.8 or later
  3. Verify the upgrade was successful by checking the installed version

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-40576 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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