RCE in Knowns-Dev Knowns
CVE-2026-86540
knowns versions before 0.30.0 fail to validate the settings.lsp.languages binary field in project configuration files, allowing attackers to execute arbitrary binaries by crafting a malicious .knowns/config.json file. When a repository with a crafted configuration is opened, the unvalidated binary path is executed twice under the user's account without any verification.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (11.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 11th percentile — 11.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.001
Affected products
Weakness classification (CWE)
References
- Detector.resolve executes the unvalidated binary override (v0.29.1) (technical-description)
- ProjectSettings.Validate does not inspect the LSP binary field (v0.29.1) (technical-description)
- knowns fix commit d3989829fb50 (patch)
- knowns v0.30.0 Release Notes (release-notes)
- GitHub Security Advisory (GHSA-mc52-mwq4-vfx3) (vendor-advisory)
- VulnCheck Advisory: knowns before 0.30.0 Arbitrary Code Execution via LSP Binary (third-party-advisory)
Frequently asked questions
- What is CVE-2026-86540?
- CVE-2026-86540 is a high-severity vulnerability in Knowns-Dev Knowns, classified under OS Command Injection. CVSS score: 7.8/10. Published 2026-09-07.
- How severe is CVE-2026-86540?
- High severity. CVSS v3 base score is 7.8 out of 10.