A post-authentication command injection vulnerability in Zyxel ATP series firmware versions from V5.00 through V5.38, USG FLEX series firmware versions from V5.00 through V5.38, USG FLEX 50(W) series firmware versions from V5.00 through V5.38, and USG20(W)-VPN series firmware versions from V5.00 through V5.38 could allow an authenticated attacker with administrator privileges to execute some OS commands on an affected device by uploading a crafted compressed language file via FTP.

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 post-authentication command injection vulnerability in Zyxel ATP series firmware versions from V4.60 through V5.38 and USG FLEX series firmware versions from V4.60 through V5.38 could allow an authenticated attacker with administrator privileges to execute some operating system (OS) commands on an affected device by executing a crafted CLI command.

A command injection vulnerability in the access point (AP) management feature of the Zyxel ATP series firmware versions 5.00 through 5.36 Patch 2, USG FLEX series firmware versions 5.00 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 5.00 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 5.00 through 5.36 Patch 2, VPN series firmware versions 5.00 through 5.36 Patch 2, NXC2500 firmware versions 6.10(AAIG.0) through 6.10(AAIG.3), and NXC5500 firmware versions 6.10(AAOS.0) through 6.10(AAOS.4), could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device if the attacker could trick an authorized administrator to add their IP address to the managed AP list in advance.

A buffer overflow vulnerability in the Zyxel ATP series firmware versions 4.32 through 5.36 Patch 2, USG FLEX series firmware versions 4.50 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 4.16 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 4.16 through 5.36 Patch 2, VPN series firmware versions 4.30 through 5.36 Patch 2, NXC2500 firmware versions 6.10(AAIG.0) through 6.10(AAIG.3), and NXC5500 firmware versions 6.10(AAOS.0) through 6.10(AAOS.4), could allow an unauthenticated, LAN-based attacker to cause denial of service (DoS) conditions by sending a crafted request to the CAPWAP daemon.

A command injection vulnerability in the Free Time WiFi hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.36 Patch 2 and VPN series firmware versions 4.20 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device.

A command injection vulnerability in the hotspot management feature of the Zyxel ATP series firmware versions 4.60 through 5.36 Patch 2, USG FLEX series firmware versions 4.60 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 4.60 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 4.60 through 5.36 Patch 2, and VPN series firmware versions 4.60 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device if the attacker could trick an authorized administrator to add their IP address to the list of trusted RADIUS clients in advance.

A format string vulnerability in the Zyxel ATP series firmware versions 5.10 through 5.36 Patch 2, USG FLEX series firmware versions 5.00 through 5.36 Patch 2, USG FLEX 50(W) series firmware versions 5.10 through 5.36 Patch 2, USG20(W)-VPN series firmware versions 5.10 through 5.36 Patch 2, and VPN series firmware versions 5.00 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands by using a crafted PPPoE configuration on an affected device when the cloud management mode is enabled.

The configuration parser fails to sanitize user-controlled input in the Zyxel ATP series firmware versions 5.10 through 5.36, USG FLEX series firmware versions 5.00 through 5.36,  USG FLEX 50(W) series firmware versions 5.10 through 5.36, USG20(W)-VPN series firmware versions 5.10 through 5.36, and VPN series firmware versions 5.00 through 5.36. An unauthenticated, LAN-based attacker could leverage the vulnerability to inject some operating system (OS) commands into the device configuration data on an affected device when the cloud management mode is enabled.