CVE-2026-36609

High severity, CVSS 7.3. EPSS: 0.2% chance of exploitation in the next 30 days.

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 uses a static authentication nonce that does not change between requests from the same source IP. Combined with the predictable XOR-based password encoding (securityEncode function), this allows an attacker to reverse captured authentication tokens to recover the plaintext password.

Published 2026-06-03. Last modified 2026-07-22.