high8.8
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 t…
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | knowns | <= 0.29.1 | 0.30.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-9gfj-28hw-jchp
- https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchp
- https://nvd.nist.gov/vuln/detail/CVE-2026-86439
- https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4e
- https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129
- https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211
- https://github.com/knowns-dev/knowns/releases/tag/v0.30.0
- https://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools