Zyxel security advisory for password guessing vulnerability of GS1200 series switches

CVE: CVE-2022-0823



Zyxel is aware that GS1200 series switches are vulnerable to password-guessing attacks. Users are advised to install the applicable updates for optimal protection.


What is the vulnerability?

An improper control of interaction frequency vulnerability in Zyxel GS1200 series switches could allow a local attacker to guess the password by using a timing side-channel attack.


What versions are vulnerable—and what should you do?

After a thorough investigation, we’ve identified the vulnerable products that are within their vulnerability support period and released hotfixes, and will release patches to address the issue, as shown in the table below.

Affected model Patch availability
Hotfix Standard firmware
GS1200-5 V2.00(ABKM.2) in Nov. 2022
GS1200-5HP V2.00(ABKN.2) in Nov. 2022
GS1200-8 V2.00(ABME.2) in Nov. 2022
GS1200-8HP V2.00(ABMF.2) in Nov. 2022

Got a question?

Please contact your local service rep or visit Zyxel’s forum for further information or assistance.



Thanks to Lars Haulin for reporting the issue to us.


Revision history

2022-06-07: Initial release