What is CVE-2020-25014?

CVE-2020-25014 is a critical-severity vulnerability in Zyxel Access Points Firmware, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2020-11-27.

How severe is CVE-2020-25014?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Buffer overflow in Zyxel Access Points Firmware

CVE-2020-25014

A stack-based buffer overflow in fbwifi_continue.cgi on Zyxel UTM and VPN series of gateways running firmware version V4.30 through to V4.55 allows remote unauthenticated attackers to execute arbitrary code via a crafted http packet.

Vulnerability class: Buffer Overflow

Published 2020-11-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.044 (91.4th percentile), scored 2026-10-23.

Low probability of exploitation in the next 30 days, but still tracked. 91st percentile — 91.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.044 · newest: 0.044 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

businessforum.zyxel.com/categories/security-news-and-release (Release Notes, Vendor Advisory)
www.zyxel.com/support/Zyxel-security-advisory-for-buffer-overflow-vulnerability… (Vendor Advisory)

Frequently asked questions

What is CVE-2020-25014?: CVE-2020-25014 is a critical-severity vulnerability in Zyxel Access Points Firmware, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2020-11-27.
How severe is CVE-2020-25014?: Critical severity. CVSS v3 base score is 9.8 out of 10.