CVE-2026-36603

Unauthenticated Access to UPnP Port Forwarding on Mercusys AC12G Router

Published Jun 3, 2026 CVSS 3.1 · 8.1 High EPSS < 1% KEV · Not listed
Description
Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 exposes 15 of 18 UPnP IGD actions without authentication on port 1900, including AddPortMapping and GetExternalIPAddress. UPnP is enabled by default through the admin interface, allowing any unauthenticated LAN device to create arbitrary port forwarding rules and access WAN traffic statistics.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Mercusys
Mercusys ac12g
Vendors & Products Mercusys
Mercusys ac12g
Type Values Removed Values Added
Title Unauthenticated Access to UPnP Port Forwarding on Mercusys AC12G Router
Type Values Removed Values Added
Title Unauthenticated Port Mapping via UPnP on Mercusys AC12G Router
Weaknesses CWE-284
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Unauthenticated Port Mapping via UPnP on Mercusys AC12G Router
Weaknesses CWE-284
CWE-306
Type Values Removed Values Added
Description Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 exposes 15 of 18 UPnP IGD actions without authentication on port 1900, including AddPortMapping and GetExternalIPAddress. UPnP is enabled by default through the admin interface, allowing any unauthenticated LAN device to create arbitrary port forwarding rules and access WAN traffic statistics.
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Jun 5, 2026, 2:04 AM
Reserved
Apr 6, 2026, 12:00 AM
Status
Deferred
Published
Jun 3, 2026, 6:16 PM
Modified
Jul 22, 2026, 7:10 PM