Vulnerability · Published Sep 4, 2026 · Assigned by VulnCheck
CVE-2026-85661excel-mcp-server 0.1.8 Arbitrary File Read/Write via stdio mode
Critical 9.8
In plain English
A critical-severity path traversal in excel-mcp-server from haris-musa. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities).
Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.7%top 47.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| haris-musa | excel-mcp-server | 0 – through 0.1.8 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
- GitHub Issue #149 issue-tracking
- https://github.com/haris-musa/excel-mcp-server product
- https://github.com/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/server.py technical-description
- https://github.com/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/validation.py technical-description
- VulnCheck Advisory: excel-mcp-server 0.1.8 Arbitrary File Read/Write via stdio mode third-party-advisory