# CVE-2026-86540

## Summary

- **CVE ID:** CVE-2026-86540
- **Severity:** HIGH
- **CVSS Score:** 8.5 (CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-78
- **Published:** Sep 7, 2026
- **Last Modified:** Sep 8, 2026

## Description

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.

## Affected Products

- knowns-dev — knowns (0)
- knowns-dev — knowns (0.30.0)

## References

- [CNA](https://github.com/knowns-dev/knowns/security/advisories/GHSA-mc52-mwq4-vfx3)
- [CNA](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/lsp/detect.go#L128-L157)
- [CNA](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/models/config.go#L205-L216)
- [CNA](https://github.com/knowns-dev/knowns/commit/d3989829fb5095666d23d005b2f78a082832a396)
- [CNA](https://github.com/knowns-dev/knowns/releases/tag/v0.30.0)
- [CNA](https://www.vulncheck.com/advisories/knowns-before-0.30.0-arbitrary-code-execution-via-lsp-binary)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.14%
- **EPSS Percentile:** 4.1

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._