CVE-2023-6399

Name: CVE-2023-6399
Creator: NVD / NIST
Published: 2024-02-20T02:15:49.407+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 0.65%

Last modified Jun 17, 2026

CVE-2023-6399 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A format string vulnerability in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from 4.16 through 5.37 Patch 1, USG20(W)-VPN series firmware versions from 4.16 through 5.37 Patch 1, and USG FLEX H series firmware versions from 1.10 through 1.10 Patch 1 could allow an authenticated IPSec VPN user to cause DoS conditions against the “deviceid” daemon by sending a crafted hostname to an affected device if it has the “Device Insight” feature enabled.. EPSS estimates a 0.65% chance of exploitation in the next 30 days.

Description

A format string vulnerability in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from 4.16 through 5.37 Patch 1, USG20(W)-VPN series firmware versions from 4.16 through 5.37 Patch 1, and USG FLEX H series firmware versions from 1.10 through 1.10 Patch 1 could allow an authenticated IPSec VPN user to cause DoS conditions against the “deviceid” daemon by sending a crafted hostname to an affected device if it has the “Device Insight” feature enabled.

Metrics

CVSS 3.1

6.5/10

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

EPSS Probability

0.65%

46.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-134

Affected Software

Vendor	Product	Versions
Zyxel	Atp100 Firmware	>= 5.10, < 5.37
Zyxel	Atp100 Firmware	5.37
Zyxel	Atp100w Firmware	>= 5.10, < 5.37
Zyxel	Atp100w Firmware	5.37
Zyxel	Atp200 Firmware	>= 5.10, < 5.37
Zyxel	Atp200 Firmware	5.37
Zyxel	Atp500 Firmware	>= 5.10, < 5.37
Zyxel	Atp500 Firmware	5.37
Zyxel	Atp700 Firmware	>= 5.10, < 5.37
Zyxel	Atp700 Firmware	5.37
Zyxel	Atp800 Firmware	>= 5.10, < 5.37
Zyxel	Atp800 Firmware	5.37
Zyxel	Usg Flex 100 Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 100 Firmware	5.37
Zyxel	Usg Flex 100ax Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 100ax Firmware	5.37
Zyxel	Usg Flex 100h Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 100h Firmware	5.37
Zyxel	Usg Flex 100w Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 100w Firmware	5.37
Zyxel	Usg Flex 200 Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 200 Firmware	5.37
Zyxel	Usg Flex 200h Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 200h Firmware	5.37
Zyxel	Usg Flex 200hp Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 200hp Firmware	5.37
Zyxel	Usg Flex 500 Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 500 Firmware	5.37
Zyxel	Usg Flex 500h Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 500h Firmware	5.37
Zyxel	Usg Flex 700 Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 700 Firmware	5.37
Zyxel	Usg Flex 700h Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 700h Firmware	5.37
Zyxel	Usg Flex 50 Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 50 Firmware	5.37
Zyxel	Usg Flex 50w Firmware	>= 5.10, < 5.37
Zyxel	Usg Flex 50w Firmware	5.37
Zyxel	Usg20-Vpn Firmware	>= 5.10, < 5.37
Zyxel	Usg20-Vpn Firmware	5.37
Zyxel	Usg20w-Vpn Firmware	>= 5.10, < 5.37
Zyxel	Usg20w-Vpn Firmware	5.37
Zyxel	Uos	1.10

References

Timeline

Published: Feb 20, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2023-6399?

How severe is CVE-2023-6399?

CVE-2023-6399 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 0.65% probability of exploitation in the next 30 days.

How do I fix CVE-2023-6399?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-6399?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST