HOMEVULNERABILITIESCVE-2017-18371
CRITICAL

CVE-2017-18371

CWE-798Published: May 2, 2019· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official Description

The ZyXEL P660HN-T1A v2 TCLinux Fw #7.3.37.6 router distributed by TrueOnline has three user accounts with default passwords, including two hardcoded service accounts: one with the username true and password true, and another with the username supervisor and password zyad1234. These accounts can be used to login to the web interface, exploit authenticated command injections, and change router settings for malicious purposes.

NVD Source

Technical Analysis

CVE-2017-18371 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

billion2 product(s)
5200w-t firmware5200w-t
zyxel4 product(s)
p660hn-t1a v2 firmwarep660hn-t1a v2p660hn-t1a v1 firmwarep660hn-t1a v1
Source: NVD CPE · 6 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://raw.githubusercontent.com/pedrib/PoC/master/advisories/zyxel_trueonline.txt
ADVISORYhttps://seclists.org/fulldisclosure/2017/Jan/40
ADVISORYhttps://ssd-disclosure.com/index.php/archives/2910
ADVISORYhttps://unit42.paloaltonetworks.com/new-mirai-variant-targets-enterprise-wireless-presentation-display-systems/
ADVISORYhttps://raw.githubusercontent.com/pedrib/PoC/master/advisories/zyxel_trueonline.txt
ADVISORYhttps://seclists.org/fulldisclosure/2017/Jan/40
ADVISORYhttps://ssd-disclosure.com/index.php/archives/2910
ADVISORYhttps://unit42.paloaltonetworks.com/new-mirai-variant-targets-enterprise-wireless-presentation-display-systems/

All References (10)

→
http://www.zyxel.com/support/announcement_unauthenticated.shtmlBroken Link
→
https://raw.githubusercontent.com/pedrib/PoC/master/advisories/zyxel_trueonline.txtExploit · Third Party Advisory
→
https://seclists.org/fulldisclosure/2017/Jan/40Exploit · Mailing List · Third Party Advisory
→
https://ssd-disclosure.com/index.php/archives/2910Exploit · Technical Description · Third Party Advisory
→
https://unit42.paloaltonetworks.com/new-mirai-variant-targets-enterprise-wireless-presentation-display-systems/Technical Description · Third Party Advisory
→
http://www.zyxel.com/support/announcement_unauthenticated.shtmlBroken Link
→
https://raw.githubusercontent.com/pedrib/PoC/master/advisories/zyxel_trueonline.txtExploit · Third Party Advisory
→
https://seclists.org/fulldisclosure/2017/Jan/40Exploit · Mailing List · Third Party Advisory
→
https://ssd-disclosure.com/index.php/archives/2910Exploit · Technical Description · Third Party Advisory
→
https://unit42.paloaltonetworks.com/new-mirai-variant-targets-enterprise-wireless-presentation-display-systems/Technical Description · Third Party Advisory

Quick Facts

CVE IDCVE-2017-18371
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-798
CISA KEVNo
Affected2 vendor(s)
PublishedMay 2, 2019

Related CVEs (CWE-798)

CVE-2021-40422
10.0
CVE-2025-20309
10.0
CVE-2026-8983
10.0
CVE-2026-45631
10.0
CVE-2026-8982
10.0
CVE-2012-6428
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2017-18371 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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