Faulty Zyxel Security Update Triggers Widespread Firewall Failures and Boot Loops

Faulty Zyxel Security Update Triggers Widespread Firewall Failures and Boot Loops

Zyxel Firewall Crisis: Critical Update Causes System-Wide Issues

A problematic security signature update is causing severe disruptions for Zyxel USG FLEX and ATP Series firewalls, according to a recent advisory from the company. The faulty update, distributed between January 24-25, has resulted in multiple critical errors, including system boot loops.

Key Issues Reported:
– Device reboot loops
– ZySH daemon failures
– Login access problems
– System LED flashing
– High CPU usage
– Gateway timeout errors
– Console command failures
– Coredump message appearances

Affected Systems:
– USG FLEX and ATP Series firewalls with active security licenses
– ZLD Firmware versions only

Unaffected Systems:
– Nebula platform devices
– USG FLEX H (uOS) series

Recovery Process:
The only confirmed solution requires:
1. Physical access to the firewall
2. RS232 serial cable connection
3. Configuration backup
4. Special firmware installation
5. Configuration restoration via web GUI

Zyxel has emphasized that this issue is not security-related (not a CVE) and is providing support through a Microsoft Teams Open Question Session on January 25th (9am-12pm and 1pm-5pm GMT+1).

Administrators are strongly advised to follow Zyxel’s detailed recovery instructions before attempting any system repairs.

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