Quick answers
- Is CVE-2026-86439 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-86439 being exploited in the wild.
- How severe is CVE-2026-86439?
- High severity, with a CVSS score of 8.8, published 7 September 2026.
- Which products and versions are affected?
- Knowns-Dev Knowns before 0.30.0; knowns (npm) SEMVER:introduced=0,fixed=0.30.0.
- Is there a fix for CVE-2026-86439?
- Yes. knowns (npm): upgrade to 0.30.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-86439 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-86439?
- Check whether you run Knowns-Dev Knowns or knowns (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- knowns (npm): upgrade to 0.30.0 or later
npm install knowns@0.30.0
Technical details
The vulnerability is a directory traversal flaw in the MCP tool argument handling within knowns versions prior to 0.30.0. The vulnerable components (doc_store.go and memory_store.go) fail to properly validate and sanitize filesystem paths supplied as tool arguments, permitting attackers to inject path traversal sequences (e.g., "../") to access arbitrary files outside the project directory. An attacker can supply malicious path arguments to read, create, overwrite, or delete any Markdown file accessible to the server process with no authentication required. The fix is available in version 0.30.0 or later.
Affected products
- knowns-dev knowns before 0.30.0
Identifiers
- CVE-2026-86439
- GHSA-9gfj-28hw-jchp
Timeline
- 2026-09-07: disclosed