Knowns MCP Path Traversal Vulnerability (CVE-2026-86439)

Multiple unrestricted path traversal vulnerabilities in Knowns MCP docs and memory tools allow arbitrary file read, write, and deletion outside the project sandbox. An authorization bypass permits deletion operations even with restricted permissions.

Disclosed 25 September 2026 · Record updated 1 October 2026

Impact

Attackers can read, write, and delete arbitrary .md files outside the project sandbox, and bypass deletion restrictions through capability misclassification.

Our coverage

A mechanical hand reaches through prison bars, fingers stretching beyond the confined cell to grasp and tear documents floating in the corridor beyond.

Vulnerabilities

Path traversal flaws let Knowns MCP agent tools escape sandbox

A GitHub advisory published on 25 September 2026 says the Knowns coding-assistant server reads, writes and deletes Markdown files outside the project folder.

25 Sept 2026

Sources

github.comhttps://github.com/advisories/GHSA-9gfj-28hw-jchp