CVE-2020-24355: Zyxel VMG5313-b30b Firmware

Critical severity, CVSS 9.8. EPSS: 2.2% chance of exploitation in the next 30 days.

Zyxel VMG5313-B30B router on firmware 5.13(ABCJ.6)b3_1127, and possibly older versions of firmware are affected by insecure permissions which allows regular and other users to create new users with elevated privileges. This is done by changing "FirstIndex" field in JSON that is POST-ed during account creation. Similar may also be possible with account deletion.

Affected products

• Zyxel VMG5313-b30b Firmware: up to and including 5.13\(abcj.6\)b3_1127

Published 2020-09-02. Last modified 2026-06-17.