CVE-2026-3871 - 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

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MEDIUM

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

Published Jun 2, 2026

6.5

MEDIUM

CVSS 3.1

EPSS 0.27%

Description

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

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

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

Zyxel

VMG4005-B50B firmware

unaffected

Version	Status	Constraints
<= 5.13(ABRL.5.4)C0	affected	-

Remediation

No remediation recorded yet.

Weaknesses (1)

CWE-120

Classic Buffer Overflow

References (2)

Link	Providers	Tags
https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-33876		Advisory
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		vendor-advisory