CVE-2017-18368
CVE-2017-18368 is a security flaw in Zyxel P660HN-T1A Routers, firewalls and routers for homes and small businesses. Attackers can run commands on Zyxel P660HN-T1A Routers from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 7 Aug 2023.[1]
Zyxel P660HN-T1A Routers is in things households have: home and small-office routers, so the fix matters at home as much as at work. Zyxel has published a fix or advice.
Description
CISA calls it a command injection in Zyxel P660HN-T1A Routers. In its words: “Zyxel P660HN-T1A routers contain a command injection vulnerability in the Remote System Log forwarding function, which is accessible by an unauthenticated user and exploited via the remote_host parameter of the ViewLog.asp page.”[1]
The CVE record adds: “The ZyXEL P660HN-T1A v1 TCLinux Fw $7.3.15.0 v001 / 3.40(ULM.0)b31 router distributed by TrueOnline has a command injection vulnerability in the Remote System Log forwarding function, which is accessible by an unauthenticated user. The vulnerability is in the ViewLog.asp page and can be exploited through the remote_host parameter.”[2]
The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Zyxel’s advisory has them[3]. CISA names the product as Zyxel P660HN-T1A Routers.
Every device with Zyxel P660HN-T1A Routers needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 7 Aug 2023, 1,558 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 28 Aug 2023 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 95%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Zyxel has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Update Zyxel P660HN-T1A Routers now.Open the router’s app, or its admin page in a browser, and look for a firmware update. Then turn on automatic updates, so the next fix arrives on its own.
- If the maker has stopped updating it, replace it.Routers stop getting fixes after a few years, and attackers keep a list of the ones that did. If there’s no newer firmware, it won’t be fixed.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 95%.[4] |
See also
Other Zyxel flaws
- CVE-2026-7273, Zyxel GS1900 Series Switches: stack-based buffer overflow ·
- CVE-2024-40891, Zyxel DSL CPE Devices: DSL CPE OS command injection ·
- CVE-2024-40890, Zyxel DSL CPE Devices: DSL CPE OS command injection ·
- CVE-2024-11667, Zyxel Multiple Firewalls: path traversal ·
- CVE-2017-6884, Zyxel EMG2926 Routers: command injection ·
Other OS command injection flaws
- CVE-2026-110447, Collabora Online – Built-in CODE Server: online – built-in CODE server OS command injection ·
- CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
- CVE-2026-83549, SonicWall SMA1000 Appliances: OS command injection ·
- CVE-2026-49869, Kestra OSS: OSS OS command injection ·
- CVE-2026-73570, Synacor Zimbra Collaboration Suite (ZCS): OS command injection ·
Every Zyxel flaw on CISA’s list · Everything added in August 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Zyxel P660HN-T1A Routers Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 7 Aug 2023.
- ^ National Institute of Standards and Technology. “CVE-2017-18368 Detail”. National Vulnerability Database, published 2 May 2019.
- ^ Zyxel. Advisories and fixes: zyxel.com, zyxel.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.945, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2017-18368”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.