Vulnerability · Published Sep 7, 2026 · Assigned by VulnCheck

CVE-2026-86439knowns before 0.30.0 Path Traversal via MCP doc and memory tools

High 8.8

In plain English

A high-severity path traversal in knowns from knowns-dev. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 65% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)1.1%top 34.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	knowns	0.30.0	GHSA-9gfj-28hw-jchp

Affected products (as reported)

Vendor	Product	Versions
knowns-dev	knowns	0 – before 0.30.0

Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-9gfj-28hw-jchp) vendor-advisory
DocStore.Get path join without containment (v0.29.1) technical-description
MemoryStore.GetInLayer path join without containment (v0.29.1) technical-description
knowns fix commit 09c5a96fd581 patch
knowns v0.30.0 Release Notes release-notes
VulnCheck Advisory: knowns before 0.30.0 Path Traversal via MCP doc and memory tools third-party-advisory