Numerous high-severity vulnerabilities in Zyxel's 4G LTE/5G NR CPE, DSL/Ethernet CPE, Fiber ONTs, Security Routers, and Wireless Extenders have been quickly fixed This article explores vulnerabilities zyxel 4g. . These vulnerabilities put devices at risk of remote command injection and denial-of-service (DoS) crashes, which could give hackers control.

CVE-2025-13942, a critical command injection bug with a CVSS v3.1 score of 9.8, is the most concerning. If WAN access and UPnP are manually enabled configurations—which are not enabled by default but are frequently found in poorly configured home or small office setups—it impacts the UPnP (Universal Plug and Play) service, allowing unauthenticated remote exploitation.

Vulnerability Breakdown for CVE Vulnerability Type Attack with CVE ID Severity (CVSS) Critical Vector Impact CVE-2025-13942 (9.8) Remote Command Injection (UPnP) Execution of OS Commands CVE-2025-13943 High Command Injection Authenticated User OS Command Execution CVE-2026-1459 High (7.2) Execution of Command Injection Authenticated Admin OS CVE-2025-11845 to 11848 Medium (4.9) Null Pointer Dereference Authenticated Admin Denial-of-Service (DoS) CVE-2025-13942 stems from improper input validation in UPnP’s SOAP handling. An attacker sends malformed SOAP requests over the WAN, injecting arbitrary OS commands without authentication. This could lead to full router compromise, data exfiltration, or pivot attacks into local networks.

CVSS metrics highlight its exploitability: Attack Complexity Low, Privileges Required None, User Interaction None.

CVE-2025-13943 and CVE-2026-1459 are sibling flaws that allow command execution through crafted inputs in web interfaces but require authenticated access at the user-level for the former and admin-level for the latter. Note: In March 2026, patches for CVE-2026-1459 will be available. Several CGI endpoints harbor four medium-severity vulnerabilities (CVE-2025-11845–11848).

By sending HTTP requests that dereference null pointers, authenticated administrators can cause crashes and service outages or reboots. Since WAN access is disabled by default, CVSS scores of 4.9 indicate minimal remote impact; however, compromised credentials increase the risk. Zyxel provides firmware for most models immediately; check the advisory for your device (e.g., NR5103, VMG Series). Turn off UPnP and WAN management unless absolutely necessary.

Use strong, unique admin passwords and monitor logs for anomalies.

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