{"vulnerability": "GHSA-9GFJ-28HW-JCHP", "sightings": [{"uuid": "60c8276d-87ad-4f22-ae54-6f5d6deef482", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "GHSA-9gfj-28hw-jchp", "type": "seen", "source": "https://gist.github.com/alon710/723cd5cd84efce7d1b7fc9c58a25b858", "content": "# CVE-2026-86439: CVE-2026-86439: Path Traversal Vulnerability in knowns MCP Document and Memory Storage\n\n> **CVSS Score:** 8.8\n> **Published:** 2026-09-25\n> **Full Report:** https://cvereports.com/reports/CVE-2026-86439\n\n## Summary\nA critical path traversal vulnerability (CWE-22) exists in knowns prior to version 0.30.0. The software fails to restrict file path arguments passed to Model Context Protocol (MCP) tools, permitting low-privilege users to escape the designated base storage directories and manipulate arbitrary markdown files on the host filesystem.\n\n## TL;DR\nUnsafe path resolution in knowns < 0.30.0 allows remote users with low privileges to read, write, and delete arbitrary markdown files on the server.\n\n## Exploit Status: POC\n\n## Technical Details\n\n- **CWE ID**: CWE-22\n- **Secondary CWE ID**: CWE-863\n- **Attack Vector**: Network\n- **CVSS v3.1 Score**: 8.8\n- **EPSS Score**: 0.01079 (1.08%)\n- **Exploit Status**: Proof of Concept Available\n- **CISA KEV Status**: Not Listed\n\n## Affected Systems\n\n- knowns prior to version 0.30.0\n- **knowns**: < 0.30.0 (Fixed in: `0.30.0`)\n\n## Mitigation\n\n- Upgrade to version 0.30.0 or higher immediately.\n- Run the knowns service under a highly restricted system user account.\n- Apply network-level restriction controls to block unauthorized MCP endpoint queries.\n\n**Remediation Steps:**\n1. Identify active installations of the knowns service running versions prior to 0.30.0.\n2. Pull the patched version 0.30.0 from official distribution repositories.\n3. Review filesystem configurations to restrict read/write access of the knowns process to the local directory only.\n4. Deploy network firewalls or load balancers to restrict access to the MCP server.\n\n## References\n\n- [GitHub Security Advisory GHSA-9gfj-28hw-jchp](https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp)\n- [Fix Patch Commit](https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e)\n- [Vulnerable Source Code - Doc Store](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129)\n- [Vulnerable Source Code - Memory Store](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211)\n- [Official v0.30.0 Release Notes](https://github.com/knowns-dev/knowns/releases/tag/v0.30.0)\n- [VulnCheck Security Advisory](https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-86439) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-09-25T20:30:32.000000Z"}]}