What is CVE-2023-34139?

CVE-2023-34139 is a high-severity vulnerability in Zyxel Usg 2200-Vpn, classified under OS Command Injection. CVSS score: 8.8/10. Published 2023-07-17.

How severe is CVE-2023-34139?

High severity. CVSS v3 base score is 8.8 out of 10.

RCE in Zyxel Usg 2200-Vpn

CVE-2023-34139

A command injection vulnerability in the Free Time WiFi hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.36 Patch 2 and VPN series firmware versions 4.20 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device.

Vulnerability class: Command Injection (OS Command Injection)

Published 2023-07-17 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.008 (54.7th percentile), scored 2026-10-23.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 54.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2023-34139?: CVE-2023-34139 is a high-severity vulnerability in Zyxel Usg 2200-Vpn, classified under OS Command Injection. CVSS score: 8.8/10. Published 2023-07-17.
How severe is CVE-2023-34139?: High severity. CVSS v3 base score is 8.8 out of 10.