USG FLEX / ATP Series - Sys Light Blinking Error [affecting fw 5.00-5.21]

Zyxel is committed to continuously updating your devices for important maintenance information. This latest release fixes all-around functions of the ATP and the USG FLEX series.
If the device is using the App Patrol signature release V1.0.0.20220310.0 on 3/11/2022,
DO NOT reboot the device until you have upgraded the device firmware
to the latest 5.21 Patch 1
Warning: DO NOT apply any firmware intermediate step!

On-Premise / Standalone Customer
DO NOT UPGRADE DEVICE HA SCENARIOS BY CLOUD FIRMWARE UPGRADE
follow the upgrade by MANUAL .bin file UPLOAD - More Info.

Nebula Cloud customers should have received the upgrade if you feel any issues feel free to be in touch with our Support Team

Firmware Upgrade Notes for devices using 4.29-4.62 Firmware Versions
Firmware Upgrade Notes for devices using 5.00-5.21 Patch 0 Firmware Versions
Firmware Upgrade Notes for devices using a "Weekly Version" Firmware Version
Firmware Upgrade Notes for devices using a date code version
Release Notes for 5.21 Patch 1

Firmware Upgrade Notes for devices using 4.29-4.62 Firmware Versions

Way 1: Online Firmware Update

Way 2: Manual Firmware Update through GUI

[It´s equal if you upgrade the firmware fix to Standby or Running Partition]
Upgrade directly to 5.21 Patch 1!

Note: Please manually update the App Patrol signature before upgrading to 5.21 Patch 1 

Configuration -> Licensing -> Signature Update
Download Firmware Package (All Model)

Firmware Upgrade Notes for devices using 5.00-5.21 Patch 0 Firmware Versions

Way 1: Online Firmware Update

Way 2: Manual Firmware Update through GUI

[It´s equal if you upgrade the firmware fix to Standby or Running Partition]
Upgrade directly to 5.21 Patch 1!

Download Firmware Package (All Model)

Firmware Upgrade Notes for devices using a "Weekly Version" Firmware Version

Please contact Support, they can assist you in sending you 5.21 Patch 1 WK11
Upgrade directly to 5.21 Patch 1!

Firmware Upgrade Notes for devices using a date code version

If your Firmware shows in the following format:
433ABFW0ITS-WK21-2019-06-11-190200148D

Firmware Version - WKXX - Date - Number

Please be in touch with our Support to verify if your fix is already included in the 5.21 Patch 1 before the upgrade.

Release Notes for 5.21 Patch 1

ZLD5.21 Patch 1 fixes the following security issues:

1.     App Patrol signature V1.0.0.20220310.0

Fixed a parsing error in the Application signature V1.0.0.20220310.0. It may drive an error condition led to connectivity disruption.

2.     Zyxel-SI-1392, Zyxel-SI-1400

An authentication bypass vulnerability was found in the CGI program of ZLD firmware that could allow an attacker to bypass the web authentication and obtain administrative access to the device.  

Affected Version: ATP Series: ZLD V4.32 Patch0 through ZLD V5.20 Patch0/USG FLEX Series: ZLD V4.50 Patch0 through ZLD V5.20 Patch0/VPN Series: ZLD V4.30 Patch0 through ZLD V5.20 Patch0

3.     Zyxel-SI-1396

A cross-site scripting (XSS) vulnerability was found in the CGI program of ZLD firmware that could allow an attacker to execute malicious scripts through the web interface.

Affected Version: ATP Series: ZLD V4.35 Patch0 through ZLD V5.20 Patch0/USG FLEX Series: ZLD V4.50 Patch0 through ZLD V5.20 Patch0/VPN Series: ZLD V4.35 Patch0 through ZLD V5.20 Patch0

Release Date: March 16th, 2022 / Supported Models: ZyWALL ATP Series/ ZyWALL USG FLEX Series