CVE-2026-36608Public exploit

Admin panel exposure via UPnP self-mapping

Published Jun 3, 2026 · Updated Jun 3, 2026

UPnP access-control failure in Mercusys AC12G (EU) V1 firmware 200909 and 210128 allows remote attackers to expose its admin panel. The AddPortMapping action accepts the router's LAN or loopback address as NewInternalClient and creates a WAN-to-port-80 forwarding rule. Reachability requires unauthenticated LAN access; the mapping persists until deletion or reboot and makes the login panel internet-accessible, while administrative access still requires credentials.

CVSS severity8.8
High
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

UPnP access-control failure in Mercusys AC12G (EU) V1 firmware 200909 and 210128 allows remote attackers to expose its admin panel. The AddPortMapping action accepts the router's LAN or loopback address as NewInternalClient and creates a WAN-to-port-80 forwarding rule. Reachability requires unauthenticated LAN access; the mapping persists until deletion or reboot and makes the login panel internet-accessible, while administrative access still requires credentials.

The record

CVE
CVE-2026-36608
Published
Jun 3, 2026
Updated
Jun 3, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-441
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 3, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.6Tymbark7372CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
8.8CISA-ADPCVSS:3.1/AV:A/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.

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No observations available

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

Weakness, pattern, technique

CWE-441Unintended Proxy or Intermediary ('Confused Deputy')

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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