Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 discloses kernel memory layout via the UPnP GetStatusInfo action. An unauthenticated attacker on the adjacent network can obtain a raw MIPS KSEG0 kernel pointer, revealing kernel memory layout and aiding further exploitation.

Unauthenticated Access to UPnP Port Forwarding on Mercusys AC12G Router

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.

DNS Rebinding Vulnerability in Mercusys AC12G Router Permits Remote Management Access

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.

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 is vulnerable to a HTTP denial of service via a low number of crafted incomplete HTTP requests, causing a persistent crash that requires physical power cycling to recover.

Hardcoded DES Key in Router Backup Enables Credential Exposure

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 encrypts configuration backups with a hardcoded DES key using single DES in ECB mode. An attacker who obtains a backup file can decrypt it to recover all stored credentials including admin password, WiFi PSK, and DDNS credentials.

Mercusys AC12G (EU) V1 router with firmware AC12G(EU)_V1_200909 allows unauthenticated brute-force attacks via the TDDP password change endpoint (code=10), which lacks the rate limiting applied to the login endpoint (code=7). An attacker on the adjacent network can attempt unlimited passwords without triggering account lockout.

Router Admin Interface Exposed to Internet via UPnP AddPortMapping

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.

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.

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 transmits DDNS credentials over plaintext HTTP with only Base64 encoding. The firmware contains no TLS implementation, allowing man-in-the-middle interception of DDNS service credentials.

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 returns 128 bytes of uninitialized buffer when receiving POST requests without SOAPAction header on UPnP port 1900, exposing internal memory to unauthenticated adjacent network attackers.

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 enables WPS 2.0 by default with a weak lockout policy (60-second lockout after 10 attempts).

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 returns 128 bytes of uninitialized internal buffer contents when receiving HTTP POST requests to undefined paths, exposing server state to unauthenticated adjacent network attackers.

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 exposes an undocumented /agileconfigreset endpoint that returns internal buffer contents to unauthenticated attackers on the adjacent network.

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 contains hardcoded WiFi driver credentials including a RADIUS shared secret, WPS test key, and default PSK embedded in the production firmware binary.

Mercusys AC12G (EU) V1 with firmware AC12G(EU)_V1_200909 responds to version.bind CHAOS TXT queries, disclosing the DNS resolver software version (unbound 1.22.0), aiding targeted attacks against known vulnerabilities.