Zywall USG FLEX Series & ATP Series - V5.42Patch 0 Firmware Release

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Zyxel_Melen
Zyxel_Melen Posts: 4,535 image  Zyxel Employee
Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate
edited February 11 in Security Gateway New Release

Zywall USG FLEX Series & ATP Series Release Note 

February 2026

Firmware Version on all models

(Click the hyperlink to find the firmware file directly)

FLEX SeriesDownload linkATP SeriesDownload link
FLEX50removedATP100removed
FLEX50WremovedATP100Wremoved
FLEX50AXremovedATP200removed
FLEX100removedATP500removed
FLEX100WremovedATP700removed
FLEX100AXremovedATP800removed
FLEX200removed
FLEX500removed
FLEX700removed

New Feature and Enhancements

S=Standalone mode, C=Cloud mode

New Feature and EnhancementsSC
1. Anti-Malware allow/block list supports SHA-256 hash value.V-
2. [eITS#250801365] Enhanced the format of the Security Policy alert email to improve readability.V-
3. [eITS#250901370] Support # and ; as a comment symbol in External Block List (EBL) entry.V-
4. Local GUI updated the i-note content for ‘Change to a Different ISP’ in cloud mode.-V

Bug Fix

S=Standalone mode, C=Cloud mode

Bug fixSC
1. eITS#250601128 a. Fix: Unexpected reboot when IPS is enabled.V-
2. eITS#250701806 a. Fix: A specific FQDN object is not taking effect in the destination of IP Exception.V-
3. eITS#250800047 a. Fix: Disabled Airtime Fairness or Overwrite Full Power settings are not saved to the startup-config.conf file and are unexpectedly re-enabled on APs after the controller is rebooted.V-
4. eITS#251001535 a. Fix: It is impossible to configure virtual interface IP after ATP800 is upgraded to 5.41.V-
5. eITS#251001984, 251100309 a. Fix: Traffic blocked due to IP-MAC binding table sync issue.V-
6. eITS#251002189 a. Fix: DHCP does not work for Built-in AP.V-
7. eITS#251201472 a. Fix: SSL Inspection is unable to flush old session and caused concurrent session is increasing until full.V-
8. Common vulnerabilities and Exposures: ZLD5.42 Patch0 is no longer vulnerable to the following CVE References: ⚫ CVE-2025-11730VV

Please refer to the Download Link for more details.

Zyxel Melen


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Comments

  • MikeForshock
    MikeForshock Posts: 60 image  Ally Member
    First Comment Friend Collector Fifth Anniversary

    Ya'll botched it again.

    Device wont load config from 5.41 and reset to default. Now a 2 hour drive after hours…

    Thanks!

  • mMontana
    mMontana Posts: 1,461 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
    edited February 7

    Sorry to read your bad experience, @MikeForshock. Would you kindly share some information about this device misbehave?

    Edit: some devices do not see into update 5.42 firmware, only 5.41.
    This apply to USG Flex 50, USG Flex 100, but not on USG-VPN 20W. This is also reflected on MyZyxel as available firmware.

    Firmwares.png

    Links above are not working for these models.

    Last edit:

    Due to this occurencies…

    https://community.zyxel.com/en/discussion/32291/atp200-no-connection-to-gateway-after-automatic-firmware-update-v5-41-to-v5-42

    https://community.zyxel.com/en/discussion/32291/atp200-no-connection-to-gateway-after-automatic-firmware-update-v5-41-to-v5-42

    Update has been pulled out?

  • alexey
    alexey Posts: 193 image  Master Member
    First Comment Friend Collector Eighth Anniversary

    Why you don't update topic and don't create new, that already this great release was rollback?

    изображение.png
  • mMontana
    mMontana Posts: 1,461 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments

    There's are the things that are not satisfying to me in this occurence:

    1: a security update is released but is specified in this announcement only at the bottom…
    2: a security update is release at thursday, which might be a good thing for allowing a weekend massive update, but on the other hand have a really small check-in period
    3: delivered issues from end users on some devices

    And after 3 days not even a "sorry for the issue, release paused, we are looking into it".

    These devices are 24/7 working (older versions did not have power switch) and gateway for securing networks and I am aware that most of the development efforts are on Flex H series.
    However communication should be better than this, this is also addressing a CVE vulnerability. Caring should be part of the development.

  • Zyxel_Melen
    Zyxel_Melen Posts: 4,535 image  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate

    Hi @alexey

    Thank you for your feedback, and we apologize for the delayed communication on this matter.

    The V5.42 Patch 0 firmware has been temporarily withdrawn while we address the reported issues. A date code firmware has been prepared to resolve the problem, and it has already been provided to you. Please let us know if you encounter any further issues after applying it.

    We have noted your feedback regarding our communication process and will work to improve. Thank you for your patience.

    Zyxel Melen


  • Zyxel_Melen
    Zyxel_Melen Posts: 4,535 image  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate

    Hi @mMontana

    Thank you for your detailed and constructive feedback. Your concerns are completely valid, and we owe the community a better response.

    The V5.42 Patch 0 firmware has been temporarily withdrawn. A date code firmware has been prepared to address the reported issues, and we will send it to you via private message shortly.

    We have taken note of your feedback on our release communication and will bring it to the team internally. Thank you for your patience and your continued support of this community.

    Zyxel Melen


  • mMontana
    mMontana Posts: 1,461 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
    edited February 9

    Sorry, @Zyxel_Melen also this was not addressed.

    USG20W-VPN/USG Flex 50W still have available 5.42 firmware on MyZyxel platform; I have updated a device which is still working without perceived issue.

    This is the "final" 5.42 firmware for this device? Or also this firmware will be superseeded from the coming one?

  • mMontana
    mMontana Posts: 1,461 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments

    I'm far from delighted to see a 6:53AM CET post about a Flex H release… And not a word from Zyxel on this thread. I know it's not something on the personal writing in this community, but seems gaving a touch o perspective about where the attention is.

  • Zyxel_Melen
    Zyxel_Melen Posts: 4,535 image  Zyxel Employee
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate
    https://community.zyxel.com/en/discussion/comment/83454#Comment_83454

    Hi @mMontana ,

    Apologies for the delayed response, and thank you for your patience.

    To clarify the firmware situation: V5.42 Patch 0 was intended to be removed, but due to a system error, it remained available on the myZyxel portal for USG20W-VPN and USG Flex 50W. We apologize for the confusion this caused.

    The good news is that V5.42 Patch 1 has been released today (February 11). This is the version we've been working on after pulling Patch 0, and it supersedes the previous release. We recommend upgrading to Patch 1 at your earliest convenience.

    https://community.zyxel.com/en/discussion/32338/zywall-usg-flex-series-atp-series-v5-42patch-1-firmware-release
    Zyxel Melen


  • mMontana
    mMontana Posts: 1,461 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments

    Thanks for the hard work of the developers for solving the issues in version 5.42 P0 and the release 5.42 P1

    However, after the botch of the files available 4th of February… how I could be possibily confident for a safe update?

    I was lucky enough saturday to arrive "late" for the earliest release (which whas thursday, in my time zone) and version 5.42 P0 was already pulled out of distribution. I was double lucky to deploy 5.42 P0 on a device that worked even 3 days without hiccups.
    How I know, less than 6 hours from the release, that something was not botched again?

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