CVE-2026-36603 Missing authorization in n/a
Unauthenticated LAN devices can create port forwarding rules and access WAN statistics due to missing authentication on UPnP IGD actions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-36603?
CVE-2026-36603 is a high-severity missing authorization vulnerability in n/a, published on 3 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-306
Which versions are affected by CVE-2026-36603?
How do I fix CVE-2026-36603?
No fix has been published for CVE-2026-36603 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-36603 being exploited?
There is no known exploitation of CVE-2026-36603 in the wild and no public exploit code.
Sources
Also known as GHSA-w7xg-p523-gcw4.