CVE-2025-7673: Zyxel EMG3525-t50b Firmware

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Zyxel EMG3525-t50b Firmware: before 5.50\(abpm.4\)c0 (fixed in 5.50\(abpm.4\)c0); before 5.50\(absl.0\)b8 (fixed in 5.50\(absl.0\)b8)
• Zyxel EMG5523-t50b Firmware: before 5.50\(abpm.4\)c0 (fixed in 5.50\(abpm.4\)c0); before 5.50\(absl.0\)b8 (fixed in 5.50\(absl.0\)b8)
• Zyxel EMG5723-t50k Firmware: before 5.50\(abom.5\)c0 (fixed in 5.50\(abom.5\)c0)
• Zyxel EMG6726-b10a Firmware: before 5.13\(abnp.6\).c (fixed in 5.13\(abnp.6\).c)
• Zyxel EX3510-b0 Firmware: before 5.17\(abup.3\)c0 (fixed in 5.17\(abup.3\)c0)
• Zyxel EX5510-b0 Firmware: before 5.15\(abqx.3\)c0 (fixed in 5.15\(abqx.3\)c0)
• Zyxel VMG1312-t20b Firmware: before 5.50\(absb.3\)c0 (fixed in 5.50\(absb.3\)c0)
• Zyxel VMG3625-t50b Firmware: before 5.50\(abpm.4\)c0 (fixed in 5.50\(abpm.4\)c0)
• Zyxel VMG3925-b10b Firmware: before 5.13\(aavf.16\)c (fixed in 5.13\(aavf.16\)c)
• Zyxel VMG3925-b10c Firmware: before 5.13\(aavf.16\)c (fixed in 5.13\(aavf.16\)c)
• Zyxel VMG3927-b50a Firmware: before 5.15\(abmt.5\)c0 (fixed in 5.15\(abmt.5\)c0)
• Zyxel VMG3927-b50b Firmware: before 5.13\(ably.6\)c0 (fixed in 5.13\(ably.6\)c0)
• Zyxel VMG3927-b60a Firmware: before 5.15\(abmt.5\)c0 (fixed in 5.15\(abmt.5\)c0)
• Zyxel VMG3927-t50k Firmware: before 5.50\(abom.5\)c0 (fixed in 5.50\(abom.5\)c0)
• Zyxel VMG4005-b50b Firmware: before 5.13\(abrl.5\)c0 (fixed in 5.13\(abrl.5\)c0)
• Zyxel VMG4927-b50a Firmware: before 5.13\(ably.6\)c0 (fixed in 5.13\(ably.6\)c0)
• Zyxel VMG8623-t50b Firmware: before 5.50\(abpm.4\)c0 (fixed in 5.50\(abpm.4\)c0)
• Zyxel VMG8825-b50a Firmware: before 5.15\(abmt.5\)c0 (fixed in 5.15\(abmt.5\)c0)
• Zyxel VMG8825-b60a Firmware: before 5.15\(abmt.5\)c0 (fixed in 5.15\(abmt.5\)c0)
• Zyxel VMG8825-BX0B Firmware: before 5.17\(abny.5\)c0 (fixed in 5.17\(abny.5\)c0)
• Zyxel VMG8825-t50k Firmware: before 5.50\(abom.5\)c0 (fixed in 5.50\(abom.5\)c0)
• Zyxel VMG8924-b10d Firmware: before 5.13\(abgq.6\)c0 (fixed in 5.13\(abgq.6\)c0)
• Zyxel XMG3927-b50a Firmware: before 5.15\(abmt.5\)c0 (fixed in 5.15\(abmt.5\)c0)
• Zyxel XMG8825-b50a Firmware: before 5.17\(abmt.5\)c0 (fixed in 5.17\(abmt.5\)c0)

Published 2025-07-16. Last modified 2026-06-17.