{"id":"CVE-2026-86439","title":"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","summary":"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…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-22"],"vendor":"knowns-dev","product":"knowns","affected":["knowns < 0.30.0"],"published":"2026-09-07","updated":"2026-09-08","sourceUpdated":"2026-09-08T19:56:50.950","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-86439","references":[{"url":"https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129","label":"disclosure@vulncheck.com"},{"url":"https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211","label":"disclosure@vulncheck.com"},{"url":"https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e","label":"disclosure@vulncheck.com"},{"url":"https://github.com/knowns-dev/knowns/releases/tag/v0.30.0","label":"disclosure@vulncheck.com"},{"url":"https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools","label":"disclosure@vulncheck.com"}],"tags":["nvd","cve.org"],"epss":0.01079,"epssPercentile":0.63578,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-09-08T12:44:18.439489Z"},"ingestedAt":"2026-09-08T15:33:26.980Z","slug":"CVE-2026-86439","body":"## Overview\n\nknowns 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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":49,"depthScoreParts":{"impact":48.4,"likelihood":0.2,"exploitation":0,"ransomware":0},"changes":[]}