CVE-2026-86543Public exploitNetwork attack vector

Unauthenticated management access via fail-open browser defaults

Published Sep 7, 2026 · Updated Sep 7, 2026

Missing authentication in the Knowns browser server before 0.30.0 allows remote attackers to access its management API without credentials. AuthManager.Middleware passes requests through when no password is configured, while the listener binds to all interfaces and /api/tunnel/start invokes tunnelMgr.Start without its own authorization check. A fresh default installation is sufficient for local-network access, and one request can publish the same unrestricted API through a public tunnel.

CVSS severity9.3
Critical
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authentication in the Knowns browser server before 0.30.0 allows remote attackers to access its management API without credentials. AuthManager.Middleware passes requests through when no password is configured, while the listener binds to all interfaces and /api/tunnel/start invokes tunnelMgr.Start without its own authorization check. A fresh default installation is sufficient for local-network access, and one request can publish the same unrestricted API through a public tunnel.

The record

CVE
CVE-2026-86543
Published
Sep 7, 2026
Updated
Sep 7, 2026
Vendor
Knowns
Product
Knowns
Classifications
CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.30.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Knowns · Knownsversion=0 <0.30.0

Published CVSS scores

9.3VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
9.8VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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