Vulnerability Monitor

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CVE-2015-6016

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.

Security Impact Summary

This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 9.8, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 4 products from zyxel, from zyxel, from zyxel and 1 other, organizations running these solutions should prioritize assessment and patching.

Historical Context

First disclosed in 2015, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.

Published

2015-12-31T05:59:14.833

Last Modified

2025-04-12T10:46:40.837

Status

Deferred

Source

[email protected]

Severity

CVSSv3.0: 9.8 (CRITICAL)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:C/I:C/A:C

Access Vector: NETWORK
Access Complexity: LOW
Authentication: NONE
Confidentiality Impact: COMPLETE
Integrity Impact: COMPLETE
Availability Impact: COMPLETE

Exploitability Score

10.0

Impact Score

10.0

Weaknesses

Type: Primary
CWE-255

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Hardware	zyxel	nbg-418n	-	Yes
Hardware	zyxel	p-660hw-t1_2	*	No
Operating System	zyxel	zynos_firmware	3.40\(axh.0\)	Yes
Operating System	zyxel	pmg5318-b20a_firmware	v100aanc0b5	Yes

References

http://www.securitytracker.com/id/1034552 ([email protected])
http://www.securitytracker.com/id/1034553 ([email protected])
http://www.securitytracker.com/id/1034554 ([email protected])
https://www.kb.cert.org/vuls/id/870744 Third Party Advisory, US Government Resource ([email protected])
https://www.kb.cert.org/vuls/id/BLUU-9ZQU2R Third Party Advisory, US Government Resource ([email protected])
http://www.securitytracker.com/id/1034552 (af854a3a-2127-422b-91ae-364da2661108)
http://www.securitytracker.com/id/1034553 (af854a3a-2127-422b-91ae-364da2661108)
http://www.securitytracker.com/id/1034554 (af854a3a-2127-422b-91ae-364da2661108)
https://www.kb.cert.org/vuls/id/870744 Third Party Advisory, US Government Resource (af854a3a-2127-422b-91ae-364da2661108)
https://www.kb.cert.org/vuls/id/BLUU-9ZQU2R Third Party Advisory, US Government Resource (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For zyxel's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.