CVE-2026-3871 PUBLISHED

Assigner: Zyxel
Reserved: 10.03.2026 Published: 02.06.2026 Updated: 02.06.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 6.5

Attack Vector	Adjacent Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	Zyxel
Product	VMG4005-B50B firmware
Versions	Default: unaffected Version <= 5.13(ABRL.5.4)C0 is affected

References

https://www.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

Problem Types

CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') CWE