Main Vulnerability Database Vulnerabilities #VU140855

Path traversal in ZyXEL Communications Corp. products - CVE-2026-14818

Published: August 4, 2026

Vulnerability identifier: #VU140855

CSH Severity: Low

CVSS v4: 8.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-14818

CWE-ID: CWE-22

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote user to perform directory traversal attacks.

The vulnerability exists due to input validation error when processing directory traversal sequences in the CLI command. A remote administrator can send a specially crafted HTTP request and upload arbitrary files on the system.

Affected software

ATP series
USG FLEX series
USG FLEX 50W
USG20W-VPN

How to mitigate CVE-2026-14818

Install updates from vendor's website.

ATP series - update to 5.43
USG FLEX series - update to 5.43
USG FLEX 50W - update to 5.43
USG20W-VPN - update to 5.43

External References

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-path-traversal-vulnerability-in-the-configuration-file-execution-cli-command-of-zld-firewalls-08-04-2026

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