# CVE-2026-85661

## Summary

- **CVE ID:** CVE-2026-85661
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-22
- **Published:** Sep 4, 2026
- **Last Modified:** Sep 14, 2026

## Description

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.

## Affected Products

- haris-musa — excel-mcp-server (0)

## References

- [CNA](https://github.com/haris-musa/excel-mcp-server/issues/149)
- [CNA](https://github.com/haris-musa/excel-mcp-server)
- [CNA](https://github.com/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/server.py)
- [CNA](https://github.com/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/validation.py)
- [CNA](https://www.vulncheck.com/advisories/excel-mcp-server-0.1.8-arbitrary-file-read-write-via-stdio-mode)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.44%
- **EPSS Percentile:** 37.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._