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Vulnerability record · CVE-2023-22916 · published 24 April 2023

CVE-2023-22916: Zyxel usg flex 100 firmware improper input validation vulnerability

Zyxel · Usg Flex 100 Firmware

The configuration parser of Zyxel ATP series firmware versions 5.10 through 5.35, USG FLEX series firmware versions 5.00 through 5.35, USG FLEX 50(W) firmware versions 5.10 through 5.35, USG20(W)-VPN firmware versions 5.10 through 5.35, and VPN series firmware versions 5.00 through 5.35, which fails to properly sanitize user input. A remote unauthenticated attacker could leverage the vulnerability to modify device configuration data, resulting in DoS conditions on an affected device if the attacker could trick an authorized administrator to switch the management mode to the cloud mode.

8.1 CVSS 3.1 High EPSS 0.69% · top 48.7% CWE-20 · Improper input validation
8.1CVSS 3.1 base score
0.69%EPSS exploitation probability, 30 days
NoNot in CISA KEV
18Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

The configuration parser of Zyxel ATP series firmware versions 5.10 through 5.35, USG FLEX series firmware versions 5.00 through 5.35, USG FLEX 50(W) firmware versions 5.10 through 5.35, USG20(W)-VPN firmware versions 5.10 through 5.35, and VPN series firmware versions 5.00 through 5.35, which fails to properly sanitize user input. A remote unauthenticated attacker could leverage the vulnerability to modify device configuration data, resulting in DoS conditions on an affected device if the attacker could trick an authorized administrator to switch the management mode to the cloud mode.

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

Affected products

18 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-of-fire Vendor Advisory
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-of-fire Vendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2023-22916), CISA KEV, FIRST EPSS (scores of 2026-10-06). This page is refreshed as NVD updates the record.