CVE-2026-86439
CVE-2026-86439
knowns versions before 0.30.0 fail to validate filesystem paths in MCP tool arguments, allowing attackers to read, create, overwrite and delete files outside the project directory. Attackers can supply path arguments containing directory traversal sequences to access arbitrary Markdown files accessible to the server process.
Vulnerability class: Path Traversal (Directory Traversal)
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Weakness classification (CWE)
References
- disclosure@vulncheck.com (technical-description)
- disclosure@vulncheck.com (technical-description)
- disclosure@vulncheck.com (patch)
- disclosure@vulncheck.com (release-notes)
- disclosure@vulncheck.com (vendor-advisory)
- disclosure@vulncheck.com (third-party-advisory)
Frequently asked questions
- What is CVE-2026-86439?
- CVE-2026-86439 is a high-severity vulnerability, classified under Path Traversal. CVSS score: 8.8/10. Published 2026-09-07.
- How severe is CVE-2026-86439?
- High severity. CVSS v3 base score is 8.8 out of 10.