# CVE-2026-86543

## Summary

- **CVE ID:** CVE-2026-86543
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N)
- **CWE:** CWE-306
- **Published:** Sep 7, 2026
- **Last Modified:** Sep 7, 2026

## Description

knowns versions before 0.30.0 serve the management API without authentication on all network interfaces by default, with no password required on fresh installations. Attackers can access the unauthenticated /api/tunnel/start endpoint to provision a public tunnel and republish the API at a publicly accessible address.

## Affected Products

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

## References

- [CNA](https://github.com/knowns-dev/knowns/security/advisories/GHSA-fc85-99vc-9c75)
- [CNA](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/server/auth.go#L80-L86)
- [CNA](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/cli/browser.go#L193-L200)
- [CNA](https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/server/routes/tunnel.go#L26-L38)
- [CNA](https://github.com/knowns-dev/knowns/commit/878a02cb7cc14f0a592fdfda7a520af3cac500fb)
- [CNA](https://github.com/knowns-dev/knowns/releases/tag/v0.30.0)
- [CNA](https://www.vulncheck.com/advisories/knowns-before-0.30.0-unauthenticated-management-api-exposure)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.44%
- **EPSS Percentile:** 37.2

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