CVE-2026-3871: Zyxel VMG4005-b50b Firmware

Medium severity, CVSS 6.5. EPSS: 0.3% chance of exploitation in the next 30 days.

A buffer overflow vulnerability in the UPnP DeletePortMapping() command in Zyxel VMG4005-B50B firmware versions through 5.13(ABRL.5.4)C0 could allow an adjacent attacker to trigger a temporary denial-of-service (DoS) condition affecting the UPnP function of the affected device.

Affected products

• Zyxel VMG4005-b50b Firmware: up to and including 5.13(ABRL.5.4)C0

Published 2026-06-02. Last modified 2026-07-22.