CVE-2026-3870

Medium

Description

A buffer overflow vulnerability in the UPnP AddPortMapping() 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.

SeverityMedium

CVSS6.5

Exploit probability—

Product

VMG4005-B50B firmware

PublishedJun 2, 2026

First seenJun 2, 2026

Weakness typeCWE-120CWE-120

How to fix

Vendor advisories

zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-buffer-overflow-vulnerabilities-in-the-upnp-function-of-certain-4g-lte-5g-nr-cpe-and-dsl-ethernet-cpe-06-02-2026

Affected products

Product	Affected versions	Fixed in
Zyxel VMG4005-B50B firmware	<= 5.13(ABRL.5.4)C0	—

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