What is CVE-2025-7673?

CVE-2025-7673 is a critical-severity vulnerability in Zyxel Emg3525-T50b, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2025-07-16.

How severe is CVE-2025-7673?

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

Buffer overflow in Zyxel Emg3525-T50b

CVE-2025-7673

A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware versions prior to V5.50(ABOM.5)C0 could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and potentially execute arbitrary code by sending a specially crafted HTTP request.

Vulnerability class: Buffer Overflow

Published 2025-07-16 · 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: 0.005 (43.5th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Weakness classification (CWE)

CWE-120 — Buffer Copy without Checking Size of Input (Classic Buffer Overflow)

References

www.zyxel.com/service-provider/global/en/zyxel-security-advisory-remote-code-ex… (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2025-7673?: CVE-2025-7673 is a critical-severity vulnerability in Zyxel Emg3525-T50b, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.8/10. Published 2025-07-16.
How severe is CVE-2025-7673?: Critical severity. CVSS v3 base score is 9.8 out of 10.