---
id: CVE-2026-85661
title: >-
  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
summary: >-
  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 read and write tools to
  access any …
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-22
vendor: haris-musa
product: excel-mcp-server
affected:
  - excel-mcp-server <= 0.1.8
published: '2026-09-04'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T17:17:45.823'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85661'
references:
  - url: 'https://github.com/haris-musa/excel-mcp-server'
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/server.py
    label: disclosure@vulncheck.com
  - url: >-
      https://github.com/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/validation.py
    label: disclosure@vulncheck.com
  - url: 'https://github.com/haris-musa/excel-mcp-server/issues/149'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/excel-mcp-server-0.1.8-arbitrary-file-read-write-via-stdio-mode
    label: disclosure@vulncheck.com
tags:
  - nvd
  - cve.org
epss: 0.00687
epssPercentile: 0.50564
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-14T19:20:06.345946Z'
ingestedAt: '2026-09-14T20:14:21.164Z'
---

## Overview

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 read and write tools to access any file accessible to the process.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.