Zyxel fixes a critical bug in its business firewall and VPN devices

Pierluigi Paganini April 01, 2022

Zyxel issued security updates for a critical vulnerability that affects some of its business firewall and VPN devices.

Networking equipment vendor Zyxel has pushed security updates for a critical flaw, tracked as CVE-2022-0342 (CVSS 9.8), that affects some of its business firewall and VPN products. The vulnerability can be exploited to take control of the devices.

“Zyxel has released patches for products affected by the authentication bypass vulnerability. Users are advised to install them for optimal protection.” reads the advisory published by the company. “An authentication bypass vulnerability caused by the lack of a proper access control mechanism has been found in the CGI program of some firewall versions. The flaw could allow an attacker to bypass the authentication and obtain administrative access of the device”

The following versions are affected by the vulnerability:

Affected seriesAffected firmwarePatch availability
USG/ZyWALLZLD V4.20 through ZLD V4.70ZLD V4.71
USG FLEXZLD V4.50 through ZLD V5.20ZLD V5.21 Patch 1
ATPZLD V4.32 through ZLD V5.20ZLD V5.21 Patch 1
VPNZLD V4.30 through ZLD V5.20ZLD V5.21
NSGV1.20 through V1.33 Patch 4Hotfix V1.33p4_WK11* available now
Standard patch V1.33 Patch 5 in May 2022

The vulnerability was reported by Alessandro Sgreccia from Tecnical Service Srl and Roberto Garcia H and Victor Garcia R from Innotec Security.

The vendor is recommending customers to install the firmware updates for optimal protection. 

The good news is that the vendor has no evidence that the vulnerability has been exploited in attacks in the wild.

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Pierluigi Paganini

(SecurityAffairs – hacking, Zyxel)

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