# What is CVE-2022-0342?

> CVE-2022-0342 is a critical-severity flaw (CVSS 9.8) in Usg40 Firmware from Zyxel, published on 28 March 2022. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 95%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2022-0342

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 78 out of 100 (High); action: Patch now. Kept up to date as the evidence changes.
- **Severity:** Critical (CVSS 9.8 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 95% (latest exploit-likelihood forecast)
- **Published:** 28 March 2022
- **Record last updated:** 4 April 2022
- **Main product:** Usg40 Firmware from Zyxel
- **Affected products:** 46

## What is CVE-2022-0342? 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

An authentication bypass vulnerability in the CGI program of Zyxel USG/ZyWALL series firmware versions 4.20 through 4.70, USG FLEX series firmware versions 4.50 through 5.20, ATP series firmware versions 4.32 through 5.20, VPN series firmware versions 4.30 through 5.20, and NSG series firmware versions V1.20 through V1.33 Patch 4, which could allow an attacker to bypass the web authentication and obtain administrative access of the device.

### What kind of flaw is it?

- CWE-287: Improper Authentication

### 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-2022-0342 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 95%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 95%, 95%, 95%, 95%, 95%, 95%, 95%.

### Timeline

- 28 March 2022: Published
- 4 April 2022: Record last updated
- 19 November 2025: Exploit likelihood fell
- 22 November 2025: Exploit likelihood jumped

### How Precursor Intelligence ranks it

CVE-2022-0342 scores **78 out of 100 (High)**, with the action "Patch now".

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-2022-0342?

The published record lists 46 products. Versions are as published: "4.20 to before 4.71" means from 4.20 up to, but not including, 4.71.

- [Usg40 Firmware](https://www.precursorintelligence.com/product/zyxel/usg40_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71
- [Nsg300 Firmware](https://www.precursorintelligence.com/product/zyxel/nsg300_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 1.20 to before 1.33, 1.33, 1.33-p4
- [Atp100](https://www.precursorintelligence.com/product/zyxel/atp100) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Atp100 Firmware](https://www.precursorintelligence.com/product/zyxel/atp100_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.32 to 5.20
- [Atp100w](https://www.precursorintelligence.com/product/zyxel/atp100w) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Atp100w Firmware](https://www.precursorintelligence.com/product/zyxel/atp100w_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.32 to 5.20
- [Atp200](https://www.precursorintelligence.com/product/zyxel/atp200) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Atp200 Firmware](https://www.precursorintelligence.com/product/zyxel/atp200_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.32 to 5.20
- [Atp500](https://www.precursorintelligence.com/product/zyxel/atp500) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Atp500 Firmware](https://www.precursorintelligence.com/product/zyxel/atp500_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.32 to 5.20
- [Atp700](https://www.precursorintelligence.com/product/zyxel/atp700) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Atp700 Firmware](https://www.precursorintelligence.com/product/zyxel/atp700_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.32 to 5.20
- [Atp800](https://www.precursorintelligence.com/product/zyxel/atp800) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Atp800 Firmware](https://www.precursorintelligence.com/product/zyxel/atp800_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.32 to 5.20
- [Nsg300](https://www.precursorintelligence.com/product/zyxel/nsg300) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg Flex 100](https://www.precursorintelligence.com/product/zyxel/usg_flex_100) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg Flex 100 Firmware](https://www.precursorintelligence.com/product/zyxel/usg_flex_100_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.50 to 5.20
- [Usg Flex 100w](https://www.precursorintelligence.com/product/zyxel/usg_flex_100w) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg Flex 100w Firmware](https://www.precursorintelligence.com/product/zyxel/usg_flex_100w_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.50 to 5.20
- [Usg Flex 200](https://www.precursorintelligence.com/product/zyxel/usg_flex_200) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg Flex 200 Firmware](https://www.precursorintelligence.com/product/zyxel/usg_flex_200_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.50 to 5.20
- [Usg Flex 500](https://www.precursorintelligence.com/product/zyxel/usg_flex_500) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg Flex 500 Firmware](https://www.precursorintelligence.com/product/zyxel/usg_flex_500_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.50 to 5.20
- [Usg Flex 700](https://www.precursorintelligence.com/product/zyxel/usg_flex_700) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg Flex 700 Firmware](https://www.precursorintelligence.com/product/zyxel/usg_flex_700_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.50 to 5.20
- [Usg40](https://www.precursorintelligence.com/product/zyxel/usg40) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg40w](https://www.precursorintelligence.com/product/zyxel/usg40w) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg40w Firmware](https://www.precursorintelligence.com/product/zyxel/usg40w_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71
- [Usg60](https://www.precursorintelligence.com/product/zyxel/usg60) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg60 Firmware](https://www.precursorintelligence.com/product/zyxel/usg60_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71
- [Usg60w](https://www.precursorintelligence.com/product/zyxel/usg60w) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Usg60w Firmware](https://www.precursorintelligence.com/product/zyxel/usg60w_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71
- [Vpn100](https://www.precursorintelligence.com/product/zyxel/vpn100) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Vpn100 Firmware](https://www.precursorintelligence.com/product/zyxel/vpn100_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.30 to before 5.21
- [Vpn1000](https://www.precursorintelligence.com/product/zyxel/vpn1000) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Vpn1000 Firmware](https://www.precursorintelligence.com/product/zyxel/vpn1000_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.30 to before 5.21
- [Vpn300](https://www.precursorintelligence.com/product/zyxel/vpn300) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Vpn300 Firmware](https://www.precursorintelligence.com/product/zyxel/vpn300_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.30 to before 5.21
- [Vpn50](https://www.precursorintelligence.com/product/zyxel/vpn50) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Vpn50 Firmware](https://www.precursorintelligence.com/product/zyxel/vpn50_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.30 to before 5.21
- [Zywall 110](https://www.precursorintelligence.com/product/zyxel/zywall_110) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Zywall 110 Firmware](https://www.precursorintelligence.com/product/zyxel/zywall_110_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71
- [Zywall 1100](https://www.precursorintelligence.com/product/zyxel/zywall_1100) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Zywall 1100 Firmware](https://www.precursorintelligence.com/product/zyxel/zywall_1100_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71
- [Zywall 310](https://www.precursorintelligence.com/product/zyxel/zywall_310) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Hardware): version not specified
- [Zywall 310 Firmware](https://www.precursorintelligence.com/product/zyxel/zywall_310_firmware) by [Zyxel](https://www.precursorintelligence.com/vendors/zyxel) (Operating system): 4.20 to before 4.71

## How do I fix CVE-2022-0342?

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 update named in the vendor’s advisory. We’ve put the advisory first in the list.
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. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [zyxel.com](https://www.zyxel.com/support/Zyxel-security-advisory-for-authentication-bypass-vulnerability-of-firewalls.shtml) (Vendor advisory)

## Questions

### What is CVE-2022-0342?

CVE-2022-0342 is a critical-severity flaw in Usg40 Firmware from Zyxel, published on 28 March 2022. 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-2022-0342?

It scores 9.8 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2022-0342 is 78 out of 100, which is High. Its action is "Patch now". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2022-0342 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 95%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2022-0342 affect?

For Usg40 Firmware from Zyxel: 4.20 to before 4.71. The record lists 46 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2022-0342?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2022-0342 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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