CVE-2025-7673: zyxel emg3525-t50b_firmware Classic Buffer Overflow

Vulnerability summary

CVE-2025-7673 is a critical (CVSS 9.8) Classic Buffer Overflow vulnerability in zyxel emg3525-t50b_firmware. EPSS estimates a 0.65% chance of exploitation in the next 30 days, higher than 50.3% of scored vulnerabilities.

Timeline

1. 16-07-2025
   PublishedVulnerability first disclosed.
2. 26-02-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.