# What is CVE-2017-18368?

> CVE-2017-18368 is a critical-severity flaw (CVSS 9.8) in P660hn-T1a V1 Firmware from Zyxel, published on 2 May 2019. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 94%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2017-18368

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 93 out of 100 (Critical); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** Critical (CVSS 9.8 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 94% (latest exploit-likelihood forecast)
- **Published:** 2 May 2019
- **Record last updated:** 5 November 2025
- **Main product:** P660hn-T1a V1 Firmware from Zyxel
- **Affected products:** 3

## What is CVE-2017-18368? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### The official description

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.

### What kind of flaw is it?

- CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data, change data and take it offline

Severity vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Is CVE-2017-18368 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 94%.

Exploit likelihood over the last 7 days: 94%, 94%, 94%, 94%, 94%, 94%, 94%.

### Timeline

- 2 May 2019: Published
- 5 November 2025: Record last updated

### How Precursor Intelligence ranks it

CVE-2017-18368 scores **93 out of 100 (Critical)**, with the action "Emergency patch".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2017-18368?

The published record lists 3 products.

- [P660hn-T1a V1 Firmware](https://www.precursorintelligence.com/product/zyxel/p660hn-t1a_v1_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 7.3.15.0
- [5200w-T Firmware](https://www.precursorintelligence.com/product/billion/5200w-t_firmware) by [Billion](https://www.precursorintelligence.com/vendors/billion) (Operating system): 7.3.8.0
- [P660hn-T1a V2 Firmware](https://www.precursorintelligence.com/product/zyxel/p660hn-t1a_v2_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 7.3.15.0

## How do I fix CVE-2017-18368?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the latest update from the vendor. The references list where the vendor has published details.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [zyxel.com](http://www.zyxel.com/support/announcement_unauthenticated.shtml) (Broken link)
- [raw.githubusercontent.com](https://raw.githubusercontent.com/pedrib/PoC/master/advisories/zyxel_trueonline.txt) (Exploit, Third-party advisory)
- [seclists.org](https://seclists.org/fulldisclosure/2017/Jan/40) (Exploit, Mailing list, Third-party advisory)
- [ssd-disclosure.com](https://ssd-disclosure.com/index.php/archives/2910) (Exploit, Technical description, Third-party advisory)
- [unit42.paloaltonetworks.com](https://unit42.paloaltonetworks.com/new-mirai-variant-targets-enterprise-wireless-presentation-display-systems/) (Technical description, Third-party advisory)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2017-18368) (Government resource)

## Questions

### What is CVE-2017-18368?

CVE-2017-18368 is a critical-severity flaw in P660hn-T1a V1 Firmware from Zyxel, published on 2 May 2019. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2017-18368?

It scores 9.8 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2017-18368 is 93 out of 100, which is Critical. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2017-18368 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 94%.

### Which versions does CVE-2017-18368 affect?

For P660hn-T1a V1 Firmware from Zyxel: 7.3.15.0. The record lists 3 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2017-18368?

Install the update the vendor names in its advisory. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2017-18368 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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