Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 does not validate the HTTP Host header, enabling DNS rebinding attacks.

published 2026-06-03 5mo ago modified 2026-07-22 3mo ago also EUVD-2026-34143

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 16%
public exploits: 0; none known

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 does not validate the HTTP Host header, enabling DNS rebinding attacks. An external attacker can rebind a domain to the router's internal IP address, extending the CORS wildcard vulnerability (Access-Control-Allow-Origin: *) to internet-originated attacks.

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CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 5mo ago (2026-06-03)

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Classification

Weakness

CWE-350 Reliance on Reverse DNS Resolution for a Security-Critical Action

References

github.com /Tymbark7372/MERCUSYS-AC12G/blob/master/advisories/CVE-2026-36604.md

Sources

CVE List CVE-2026-36604
NVD CVE-2026-36604

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