CVE-2026-3870

MediumCVSS 6.5

Published: 02/06/2026(UTC)Updated: 22/07/2026(UTC)Translated: 25/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.17%

6th percentile - higher than 6% of all known CVEs

Summary

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.

Risk Assessment

A DoS attack on the UPnP function can disrupt network services such as port forwarding, potentially affecting application availability.

Recommendation

Update the Zyxel router firmware to a patched version or disable UPnP if not needed.

Other vulnerabilities in Zyxel VMG4005-B50B

CVE-2026-3871Medium
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.

Original NVD description (English source)

Vulnerability data from NVD (NIST) · CISA KEV · EPSS