High severity8.8NVD Advisory· Published Sep 7, 2026· Updated Sep 8, 2026
CVE-2026-86439
CVE-2026-86439
Description
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
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
knownsnpm | < 0.30.0 | 0.30.0 |
Affected products
2- Range: <0.30.0
Patches
Vulnerability mechanics
References
8- github.com/advisories/GHSA-9gfj-28hw-jchpghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-86439ghsaADVISORY
- github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.gonvdWEB
- github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.gonvdWEB
- github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4envdWEB
- github.com/knowns-dev/knowns/releases/tag/v0.30.0nvdWEB
- github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchpnvdWEB
- www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-toolsnvdWEB
News mentions
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