A reflected cross-site scripting (XSS) vulnerability in the CGI program "dynamic_script.cgi" of Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V4.16 through V5.38, and USG20(W)-VPN series firmware versions from V4.16 through V5.38 could allow an attacker to trick a user into visiting a crafted URL with the XSS payload. The attacker could obtain browser-based information if the malicious script is executed on the victim’s browser.

A buffer overflow vulnerability in the CGI program of Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V4.16 through V5.38, and USG20(W)-VPN series firmware versions from V4.16 through V5.38 could allow an authenticated attacker with administrator privileges to cause denial of service (DoS) conditions by sending a crafted HTTP request to a vulnerable device.

A post-authentication command injection vulnerability in Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V4.16 through V5.38, and USG20(W)-VPN series firmware versions from V4.16 through V5.38 could allow an authenticated attacker with administrator privileges to execute some OS commands on an affected device by uploading a crafted internal user agreement file to the vulnerable device.

A null pointer dereference vulnerability in Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V5.20 through V5.38, and USG20(W)-VPN series firmware versions from V5.20 through V5.38 could allow an unauthenticated attacker to cause DoS conditions by sending crafted packets to a vulnerable device.

A command injection vulnerability in the IPSec VPN feature of Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V4.16 through V5.38, and USG20(W)-VPN series firmware versions from V4.16 through V5.38 could allow an unauthenticated attacker to execute some OS commands on an affected device by sending a crafted username to the vulnerable device. Note that this attack could be successful only if the device was configured in User-Based-PSK authentication mode and a valid user with a long username exceeding 28 characters exists.

An improper privilege management vulnerability in the hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.37 and VPN series firmware versions 4.30 through 5.37 could allow an authenticated local attacker to access the system files on an affected device.

An improper privilege management vulnerability in the debug CLI command of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, VPN series firmware versions 4.30 through 5.37, NWA50AX firmware version 6.29(ABYW.2), WAC500 firmware version 6.65(ABVS.1), WAX300H firmware version 6.60(ACHF.1), and WBE660S firmware version 6.65(ACGG.1), could allow an authenticated local attacker to access the administrator’s logs on an affected device.

An improper privilege management vulnerability in the ZySH of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an authenticated local attacker to modify the URL of the registration page in the web GUI of an affected device.

An integer overflow vulnerability in the source code of the QuickSec IPSec toolkit used in the VPN feature of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions on an affected device by sending a crafted IKE packet.

A buffer overflow vulnerability in the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an authenticated local attacker to cause denial-of-service (DoS) conditions by executing the CLI command to dump system logs on an affected device.

An improper privilege management vulnerability in the debug CLI command of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, VPN series firmware versions 4.30 through 5.37, NWA50AX firmware version 6.29(ABYW.2), WAC500 firmware version 6.65(ABVS.1), WAX300H firmware version 6.60(ACHF.1), and WBE660S firmware version 6.65(ACGG.1), could allow an authenticated local attacker to access system files on an affected device.

An improper input validation vulnerability in the “Quagga” package of the Zyxel ATP series firmware versions 4.32 through 5.37, USG FLEX series firmware versions 4.50 through 5.37, USG FLEX 50(W) series firmware versions 4.16 through 5.37, USG20(W)-VPN series firmware versions 4.16 through 5.37, and VPN series firmware versions 4.30 through 5.37, could allow an authenticated local attacker to access configuration files on an affected device.

Certain Zyxel products allow command injection by an admin via an input string to chg_exp_pwd during a password-change action. This affects VPN On-premise before ZLD V4.39 week38, VPN Orchestrator before SD-OS V10.03 week32, USG before ZLD V4.39 week38, USG FLEX before ZLD V4.55 week38, ATP before ZLD V4.55 week38, and NSG before 1.33 patch 4.

A stack-based buffer overflow in fbwifi_continue.cgi on Zyxel UTM and VPN series of gateways running firmware version V4.30 through to V4.55 allows remote unauthenticated attackers to execute arbitrary code via a crafted http packet.