CVE-2026-85661 json
excel-mcp-server 0.1.8 Arbitrary File Read/Write via stdio mode
published 2026-09-04 2 mo ago modified 2026-09-23 46 d ago also EUVD-2026-71117
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 52%
- public exploits
- 0
- none known
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 file accessible to the process.
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 55 d ago
Exploit prediction
0.69% chance of exploitation in the next 30 days, higher than 52% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.3 | 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 |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 9.3 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected products
- haris-musa excel-mcp-server
Classification
- Weakness
-
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory
References
-
github.com
/haris-musa/excel-mcp-server/issues/149
issue-tracking
-
github.com
/haris-musa/excel-mcp-server
product
-
github.com
/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/server.py
technical-description
-
github.com
/haris-musa/excel-mcp-server/blob/v0.1.8/src/excel_mcp/validation.py
technical-description
-
vulncheck.com
/advisories/excel-mcp-server-0.1.8-arbitrary-file-read-write-via-stdio-mode
third-party-advisory
Sources
- CVE List CVE-2026-85661
- NVD CVE-2026-85661
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.