CVE-2020-15337

Vulnerability

The vulnerability exists in the /registerCpe endpoint of Zyxel CloudCNM SecuManager versions 3.1.0 and 3.1.1. The application uses HTTP GET requests with sensitive query strings, transmitting credentials (such as usernames and passwords) as URL parameters. This violates the principle that sensitive data should never be placed in URLs, as query strings may be logged, cached, or transmitted in plaintext over the network. The affected code path is reachable by default in the web management interface.

Exploitation

An attacker with network position to observe HTTP traffic (e.g., on a shared LAN, via ARP spoofing, or through a compromised router) can capture the GET request to /registerCpe. The URL will contain sensitive parameters in the query string. The attacker does not require authentication or prior access to the device. No user interaction beyond normal traffic generation is needed; any legitimate registration attempt will expose the credentials.

Impact

Successful exploitation results in disclosure of the username and password used for device registration with the CloudCNM management platform. This credential leak can enable further compromise of the SecuManager instance and potentially managed security gateways, depending on the privileges associated with the exposed account. The confidentiality of the management credentials is breached, leading to a loss of confidentiality and possible lateral movement.

Mitigation

As of the publication date (2020-06-26), no official patch had been released by Zyxel. According to the advisory [1], the vendor was notified but no fix was available at the time. Users should restrict network access to the SecuManager management interface to trusted hosts and employ encrypted channels (e.g., VPN) to prevent traffic sniffing. Monitor HTTP logs for suspicious GET requests with long query strings. This CVE is not listed in CISA's Known Exploited Vulnerabilities catalog as of this writing.