CVE-2015-6016: Critical – ZyXEL P-660HW-T1 2 devices with ZyNOS firmware 3.40(AXH.0)

CWE Weakness Definitions

CWE-255: CWE-255

◆ AI Analysis — automated analysis, not human-reviewed

This vulnerability was disclosed in 2015. A critical vulnerability affects Zyxel systems (CVE-2015-6016). No public exploit code is currently available. Isolate affected systems if patching is not feasible.

BSID: BS-2015-GLOBAL-259860-C • Model: rule-based-v1 • Confidence: MEDIUM

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Frequently Asked Questions

What is CVE-2015-6016?

This vulnerability was disclosed in 2015. A critical vulnerability affects Zyxel systems (CVE-2015-6016). No public exploit code is currently available. Isolate affected systems if patching is not feasible.

What is the CVSS score for CVE-2015-6016?

CVE-2015-6016 has CVSS 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS: 5.7%.

Is CVE-2015-6016 actively exploited?

No confirmed active exploitation of CVE-2015-6016 as of 2026-09-25.

How do I remediate CVE-2015-6016?

Priority: MEDIUM.

What systems are affected by CVE-2015-6016?

CVE-2015-6016 affects: Zyxel, Zyxel, Zyxel, Zyxel.

Vulnerability Details

CVE ID	`CVE-2015-6016`
BSID	`BS-2015-GLOBAL-259860-C` BreachSpider Global ID
CVSS Vector	`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
Published	2015-12-31
Last Modified	2026-06-17
ICS Relevance	75%
Weakness (CWE)	CWE-255
Domains	NETWORK-INFRA
Source	NVD

Official Description

ZyXEL P-660HW-T1 2 devices with ZyNOS firmware 3.40(AXH.0), PMG5318-B20A devices with firmware 1.00AANC0b5, and NBG-418N devices have a default password of 1234 for the admin account, which allows remote attackers to obtain administrative access via unspecified vectors.

Source: NIST NVD / MITRE CVE Database

Attack Vector Analysis — CITED Relevance

Vulnerability details: ZyXEL P-660HW-T1 2 devices with ZyNOS firmware 3.40(AXH.0), PMG5318-B20A devices with firmware 1.00AANC0b5, and NBG-418N devices have a default password of 1234 for the admin account, which allows remote attackers to obtain administrative access via unspecified vectors. CVSS vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Exploitation Likelihood: LOW

Affected Products

Vendor	Product	Fixed Version
Zyxel	Nbg-418N	—
Zyxel	P-660Hw-T1 2	—
Zyxel	Zynos Firmware	—
Zyxel	Pmg5318-B20A Firmware	—

Remediation

No patch URL on record. Monitor vendor security advisories directly.

Threat Intelligence

● Threat Intelligence Validated: September 2026 | Threat Age: 3924 Days

CISA KEV	Not in KEV catalog
Public Exploit	Not confirmed
PoC Code	Not confirmed

AI Enrichment Record — provenance & audit hash

Model	`rule-based-v1`
Confidence	MEDIUM
Enriched At	2026-05-24
SHA-512 Audit Hash	`025da9ad1e00be7cbf7b9fb3b583385d24727eb7a24de1e93d135f6496c678b5a2d4ae8eba8076f664bb0d68e0ecf4d780ba761a02a9241f71d0341f15dfe1fe`

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