An authentication bypass vulnerability in the CGI program of Zyxel USG/ZyWALL series firmware versions 4.20 through 4.70, USG FLEX series firmware versions 4.50 through 5.20, ATP series firmware versions 4.32 through 5.20, VPN series firmware versions 4.30 through 5.20, and NSG series firmware versions V1.20 through V1.33 Patch 4, which could allow an attacker to bypass the web authentication and obtain administrative access of the device.

WiMAX routers based on the MediaTek SDK (libmtk) that use a custom httpd plugin are vulnerable to an authentication bypass allowing a remote, unauthenticated attacker to gain administrator access to the device by performing an administrator password change on the device via a crafted POST request.

An authentication bypasss vulnerability in the web-based management interface of Zyxel USG/Zywall series firmware versions 4.35 through 4.64 and USG Flex, ATP, and VPN series firmware versions 4.35 through 5.01, which could allow a remote attacker to execute arbitrary commands on an affected device.

The ZyXEL P660HN-T1A v2 TCLinux Fw #7.3.37.6 router distributed by TrueOnline has three user accounts with default passwords, including two hardcoded service accounts: one with the username true and password true, and another with the username supervisor and password zyad1234. These accounts can be used to login to the web interface, exploit authenticated command injections, and change router settings for malicious purposes.

Cisco NX-OS 6.0(2)U6(1) through 6.0(2)U6(5) on Nexus 3000 devices and 6.0(2)A6(1) through 6.0(2)A6(5) and 6.0(2)A7(1) on Nexus 3500 devices has hardcoded credentials, which allows remote attackers to obtain root privileges via a (1) TELNET or (2) SSH session, aka Bug ID CSCuy25800.

ZyXEL P-660HW-T1 2 devices with ZyNOS firmware 3.40(AXH.0), PMG5318-B20A devices with firmware 1.00AANC0b5, and NBG-418N devices have a default password of 1234 for the admin account, which allows remote attackers to obtain administrative access via unspecified vectors.

The web management interface on Belkin F9K1102 2 devices with firmware 2.10.17 has a blank password, which allows remote attackers to obtain administrative privileges by leveraging a LAN session.

The diagnostic-ping implementation on ZyXEL PMG5318-B20A devices with firmware before 1.00(AANC.2)C0 allows remote attackers to execute arbitrary commands via the PingIPAddr parameter.

Belkin F9K1102 2 devices with firmware 2.10.17 rely on client-side JavaScript code for authorization, which allows remote attackers to obtain administrative privileges via certain changes to LockStatus and Login_Success values.

ZyXEL Prestige 642R and 642R-I routers do not filter the routers' Telnet and FTP ports on the external WAN interface from inside access, allowing someone on an internal computer to reconfigure the router, if the password is known.

Zyxel CloudCNM SecuManager 3.1.0 and 3.1.1 has the axiros password for the root account.

The UPnP IGD implementation in the Pseudo ICS UPnP software on the ZyXEL P-330W allows remote attackers to establish arbitrary port mappings by sending a UPnP AddPortMapping action in a SOAP request to the WAN interface, related to an "external forwarding" vulnerability.

The rpWLANRedirect.asp ASP page is accessible without authentication on ZyXEL P-660HN-T1 V2 (2.00(AAKK.3)) devices. After accessing the page, the admin user's password can be obtained by viewing the HTML source code, and the interface of the modem can be accessed as admin.

ZyXEL ZyWALL 1050 has a hard-coded password for the Quagga and Zebra processes that is not changed when it is set by a user, which allows remote attackers to gain privileges.

ZyXEL Prestige routers, including P-660, P-661, and P-662 models with firmware 3.40(PE9) and 3.40(AGD.2) through 3.40(AHQ.3), support authentication over HTTP via a hash string in the hiddenPassword field, which allows remote attackers to obtain access via a replay attack.

The SNMP service on ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), has "public" as its default community for both (1) read and (2) write operations, which allows remote attackers to perform administrative actions via SNMP, as demonstrated by reading the Dynamic DNS service password or inserting an XSS sequence into the system.sysName.0 variable, which is displayed on the System Status page.

ZyXEL Prestige routers, including P-660 and P-661 models with firmware 3.40(AGD.2) through 3.40(AHQ.3), have (1) "user" as their default password for the "user" account and (2) "1234" as their default password for the "admin" account, which makes it easier for remote attackers to obtain access.

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.

Zyxel CloudCNM SecuManager 3.1.0 and 3.1.1 has the axzyxel password for the livedbuser account.

Zyxel CloudCNM SecuManager 3.1.0 and 3.1.1 has the wbboEZ4BN3ssxAfM hardcoded password for the debian-sys-maint account.

Zyxel CloudCNM SecuManager 3.1.0 and 3.1.1 has a world-readable axess/opt/axXMPPHandler/config/xmpp_config.py file that stores hardcoded credentials.

Zyxel CloudCNM SecuManager 3.1.0 and 3.1.1 has the cloud1234 password for the a1@chopin account default credentials.

ZyXEL P-335WT router allows remote attackers to bypass access restrictions and conduct unauthorized operations via a UPnP request with a modified InternalClient parameter, which is not validated, as demonstrated by using AddPortMapping to forward arbitrary traffic.

wan.htm page on Zyxel NBG-418N v2 with firmware version V1.00(AARP.9)C0 can be accessed directly without authentication, which can lead to disclosure of information about the WAN, and can also be leveraged by an attacker to modify data fields of the page.

ZyXEL VMG3312-B10B 1.00(AAPP.7) devices have a backdoor root account with the tTn3+Z@!Sr0O+ password hash in the etc/default.cfg file.

This vulnerability allows remote attackers to cause a denial-of-service condition on vulnerable installations of ZyXEL P-870H-51 DSL Router 1.00(AWG.3)D5. Authentication is not required to exploit this vulnerability. The specific flaw exists within numerous exposed CGI endpoints. The vulnerability is caused by improper access controls that allow access to critical functions without authentication. An attacker can use this vulnerability to reboot affected devices, along with other actions. Was ZDI-CAN-4540.

The ZyXEL Wireless N300 NetUSB NBG-419N router with firmware 1.00(BFQ.6)C0 allows remote attackers to execute arbitrary code via shell metacharacters in input to the (1) detectWeather, (2) set_language, (3) SystemCommand, or (4) NTPSyncWithHost function in management.c, or a (5) SET COUNTRY, (6) SET WLAN SSID, (7) SET WLAN CHANNEL, (8) SET WLAN STATUS, or (9) SET WLAN COUNTRY udps command.

A command injection vulnerability in the CGI program of the Zyxel VPN2S firmware version 1.12 could allow an authenticated, local user to execute arbitrary OS commands.

** UNSUPPORTED WHEN ASSIGNED ** A command injection vulnerability in the CGI program of Zyxel WRE6505 v2 firmware version V1.00(ABDV.3)C0 could allow an adjacent attacker on the LAN to execute operating system (OS) commands on a vulnerable device by sending a crafted HTTP request.

The ZyXEL P660HN-T1A v1 TCLinux Fw $7.3.15.0 v001 / 3.40(ULM.0)b31 router distributed by TrueOnline has a command injection vulnerability in the Remote System Log forwarding function, which is accessible by an unauthenticated user. The vulnerability is in the ViewLog.asp page and can be exploited through the remote_host parameter.

The Billion 5200W-T TCLinux Fw $7.3.8.0 v008 130603 router distributed by TrueOnline has a command injection vulnerability in the Time Setting function, which is only accessible by an authenticated user. The vulnerability is in the tools_time.asp page and can be exploited through the uiViewSNTPServer parameter. Authentication can be achieved by exploiting CVE-2017-18373.

The ZyXEL P660HN-T1A v2 TCLinux Fw #7.3.37.6 router distributed by TrueOnline has a command injection vulnerability in the Remote System Log forwarding function, which is only accessible by an authenticated user. The vulnerability is in the logSet.asp page and can be exploited through the ServerIP parameter. Authentication can be achieved by exploiting CVE-2017-18371.

A post-authentication command injection vulnerability in the log file download function of the Zyxel EX3301-T0 firmware versions through 5.50(ABVY.7)C0 could allow an authenticated attacker to execute operating system (OS) commands on an affected device.

Multiple ZyXEL network-attached storage (NAS) devices running firmware version 5.21 contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable device. ZyXEL NAS devices achieve authentication by using the weblogin.cgi CGI executable. This program fails to properly sanitize the username parameter that is passed to it. If the username parameter contains certain characters, it can allow command injection with the privileges of the web server that runs on the ZyXEL device. Although the web server does not run as the root user, ZyXEL devices include a setuid utility that can be leveraged to run any command with root privileges. As such, it should be assumed that exploitation of this vulnerability can lead to remote code execution with root privileges. By sending a specially-crafted HTTP POST or GET request to a vulnerable ZyXEL device, a remote, unauthenticated attacker may be able to execute arbitrary code on the device. This may happen by directly connecting to a device if it is directly exposed to an attacker. However, there are ways to trigger such crafted requests even if an attacker does not have direct connectivity to a vulnerable devices. For example, simply visiting a website can result in the compromise of any ZyXEL device that is reachable from the client system. Affected products include: NAS326 before firmware V5.21(AAZF.7)C0 NAS520 before firmware V5.21(AASZ.3)C0 NAS540 before firmware V5.21(AATB.4)C0 NAS542 before firmware V5.21(ABAG.4)C0 ZyXEL has made firmware updates available for NAS326, NAS520, NAS540, and NAS542 devices. Affected models that are end-of-support: NSA210, NSA220, NSA220+, NSA221, NSA310, NSA310S, NSA320, NSA320S, NSA325 and NSA325v2

The post-authentication command injection vulnerability in the CLI command of Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.16 through 5.35, USG20(W)-VPN firmware versions 4.16 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow an authenticated attacker to execute some OS commands remotely.

Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.

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.

The pre-authentication command injection vulnerability in the Zyxel NAS326 firmware versions prior to V5.21(AAZF.14)C0, NAS540 firmware versions prior to V5.21(AATB.11)C0, and NAS542 firmware versions prior to V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands remotely by sending a crafted HTTP request.

The post-authentication command injection vulnerability in the Zyxel NBG6604 firmware version V1.01(ABIR.0)C0 could allow an authenticated attacker to execute some OS commands remotely by sending a crafted HTTP request.

A post-authentication command injection vulnerability in the "host" parameter of the diagnostic function in Zyxel VMG4005-B50A firmware versions through V5.15(ABQA.2.2)C0 could allow an authenticated attacker with administrator privileges to execute operating system (OS) commands on a vulnerable device.

A post-authentication command injection vulnerability in the CGI program in the Zyxel GS1900-48 switch firmware version V2.80(AAHN.1)C0 and earlier could allow an authenticated, LAN-based attacker with administrator privileges to execute some operating system (OS) commands on an affected device by sending a crafted HTTP request.

** UNSUPPORTED WHEN ASSIGNED ** A command injection vulnerability in the functions formSysCmd(), formUpgradeCert(), and formDelcert() in the Zyxel NWA1100-N firmware version 1.00(AACE.1)C0 could allow an unauthenticated attacker to execute some OS commands to access system files on an affected device.

The improper neutralization of special elements in the parameter "host" in the CGI program of Zyxel NWA1123ACv3 firmware version 6.70(ABVT.4) and earlier, WAC500 firmware version 6.70(ABVS.4) and earlier, WAX655E firmware version 7.00(ACDO.1) and earlier, WBE530 firmware version 7.00(ACLE.1) and earlier, and USG LITE 60AX firmware version V2.00(ACIP.2) could allow an unauthenticated attacker to execute OS commands by sending a crafted cookie 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.

**UNSUPPORTED WHEN ASSIGNED** A command injection vulnerability in the export-cgi program of Zyxel NAS326 firmware versions through V5.21(AAZF.18)C0 and NAS542 firmware versions through V5.21(ABAG.15)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted HTTP POST request.

A command injection vulnerability in the CGI program of Zyxel NR7101 firmware prior to V1.15(ACCC.3)C0, which could allow an authenticated attacker to execute some OS commands on a vulnerable device by sending a crafted HTTP request.

A post-authentication command injection vulnerability in the CLI command of Zyxel ZyWALL/USG series firmware versions 4.20 through 4.72, VPN series firmware versions 4.30 through 5.32, USG FLEX series firmware versions 4.50 through 5.32, and ATP series firmware versions 4.32 through 5.32, which could allow an authenticated attacker with administrator privileges to execute OS commands.