Vulnerabilities

** UNSUPPORTED WHEN ASSIGNED ** A buffer overflow vulnerability in the formWep(), formWlAc(), formPasswordSetup(), formUpgradeCert(), and formDelcert() functions of the “webs” binary in Zyxel NWA1100-N customized firmware version 1.00(AACE.1)C0 could allow an attacker to trigger a denial-of-service (DoS) condition by sending a crafted HTTP request to a vulnerable device.

** 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.

A post-authentication command injection vulnerability in the “DomainName” parameter of the DHCP configuration file in Zyxel DX3301-T0 and EX3301-T0 firmware versions through 5.50(ABVY.7.1)C0 could allow an authenticated attacker with administrator privileges to execute OS commands on an affected device.

A post-authentication command injection vulnerability in the EasyMesh-related APIs of Zyxel DX3300-T0 firmware versions through 5.50(ABVY.7.1)C0 could allow an authenticated, adjacent attacker with administrator privileges to execute OS commands on an affected device.

** UNSUPPORTED WHEN ASSIGNED ** An improper encoding or escaping vulnerability in the CGI program of Zyxel WRE6505 v2 firmware version V1.00(ABDV.3)C0 could allow an adjacent attacker on the WLAN to cause a denial-of-service (DoS) condition in the web management interface by convincing an authenticated administrator to visit the “AP Select” page while a malformed SSID is present.

A post-authentication command injection vulnerability in the TR-369 certificate download CGI program of the Zyxel VMG3625-T50B firmware versions through 5.50(ABPM.9.7)C0 could allow an authenticated attacker with administrator privileges to execute operating system (OS) commands on an affected device.

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.

A command injection vulnerability in the UPnP function of the Zyxel EX3510-B0 firmware versions through 5.17(ABUP.15.1)C0 could allow a remote attacker to execute operating system (OS) commands on an affected device by sending specially crafted UPnP SOAP requests.

A null pointer dereference vulnerability in the IP settings CGI program of the Zyxel VMG3625-T50B firmware versions through 5.50(ABPM.9.6)C0 and the Zyxel WX3100-T0 firmware versions through 5.50(ABVL.4.8)C0 could allow an authenticated attacker with administrator privileges to trigger a denial-of-service (DoS) condition by sending a crafted HTTP request.

A null pointer dereference vulnerability in the account settings CGI program of the Zyxel VMG3625-T50B firmware versions through 5.50(ABPM.9.6)C0 and the Zyxel WX3100-T0 firmware versions through 5.50(ABVL.4.8)C0 could allow an authenticated attacker with administrator privileges to trigger a denial-of-service (DoS) condition by sending a crafted HTTP request.

A post-authentication command injection vulnerability in the "priv" parameter of Zyxel DX3300-T0 firmware version 5.50(ABVY.6.3)C0 and earlier could allow an authenticated attacker to execute operating system (OS) commands on an affected device.

An uncontrolled resource consumption vulnerability in the web server of Zyxel DX3301-T0 firmware version 5.50(ABVY.6.3)C0 and earlier could allow an attacker to perform Slowloris‑style denial‑of‑service (DoS) attacks. Such attacks may temporarily block legitimate HTTP requests and partially disrupt access to the web management interface, while other networking services remain unaffected.

A missing authorization vulnerability in Zyxel ATP series firmware versions from V4.32 through V5.40, USG FLEX series firmware versions from V4.50 through V5.40, USG FLEX 50(W) series firmware versions from V4.16 through V5.40, and USG20(W)-VPN series firmware versions from V4.16 through V5.40 could allow a semi-authenticated attacker—who has completed only the first stage of the two-factor authentication (2FA) process—to view and download the system configuration from an affected device.

A buffer overflow vulnerability in the URL parser of the zhttpd web server in Zyxel VMG8825-T50K firmware versions prior to V5.50(ABOM.5)C0 could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and potentially execute arbitrary code by sending a specially crafted HTTP request.

A path traversal vulnerability in the file_upload-cgi CGI program of Zyxel NWA50AX PRO firmware version 7.10(ACGE.2) and earlier could allow an authenticated attacker with administrator privileges to access specific directories and delete files, such as the configuration file, on the affected device.

**UNSUPPORTED WHEN ASSIGNED** A path traversal vulnerability in the web management interface of the Zyxel AMG1302-T10B firmware version 2.00(AAJC.16)C0 could allow an authenticated attacker with administrator privileges to access restricted directories by sending a crafted HTTP request to an affected device.

An incorrect permission assignment vulnerability in the PostgreSQL commands of the Zyxel USG FLEX H series uOS firmware versions from V1.20 through V1.31 could allow an authenticated local attacker with low privileges to gain access to the Linux shell and escalate their privileges by crafting malicious scripts or modifying system configurations with administrator-level access through a stolen token. Modifying the system configuration is only possible if the administrator has not logged out and the token remains valid.

A post-authentication command injection vulnerability in the ”zyUtilMailSend” function of the Zyxel AX7501-B1 firmware version V5.17(ABPC.5.3)C0 and earlier 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 "ZyEE" function of the Zyxel EX5601-T1 firmware version V5.70(ACDZ.3.6)C0 and earlier 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 "DNSServer” parameter of the diagnostic function in the Zyxel VMG8825-T50K firmware version V5.50(ABOM.8.5)C0 and earlier could allow an authenticated attacker with administrator privileges to execute operating system (OS) commands on a vulnerable device.

**UNSUPPORTED WHEN ASSIGNED** Insecure default credentials for the Telnet function in the legacy DSL CPE Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615 could allow an attacker to log in to the management interface if the administrators have the option to change the default credentials but fail to do so.

Multiple Zyxel DSL CPE devices contain an OS command injection flaw (CWE-78) in a CGI program, where insufficient input handling lets a crafted HTTP request execute arbitrary operating-system commands. Because the flaw is post-authentication, an attacker needs valid credentials on the device's web management interface to trigger it, but can then run commands with the privileges of the device's web server, enabling configuration changes, persistence, or pivoting to the ISP subscriber network. Only Zyxel DSL CPE devices are affected; the specific models and firmware versions have not been detailed in the available data, and CISA notes impacted products may be end-of-life or end-of-service. The vulnerability was added to the CISA Known Exploited Vulnerabilities catalog on 2025-02-11, confirming exploitation in the wild, though no public proof-of-concept is known and ransomware use has not been observed. EPSS assigns a 22.3% probability of exploitation within 30 days (98th percentile), indicating elevated exploitation risk.

Do: Inventory all Zyxel DSL CPE devices and check them against Zyxel's advisory to identify affected models, then apply the latest available firmware; since many affected products may be end-of-life or end-of-service, plan replacement or discontinuation of use where no patched firmware or mitigation exists (as CISA's KEV required action directs). In the interim, restrict the device's HTTP/HTTPS management interface to trusted networks, disable remote/WAN-side administration, and ensure strong, non-default admin credentials since exploitation requires authentication.

An improper privilege management vulnerability in the web management interface of the Zyxel WBE530 firmware versions through 7.00(ACLE.3) and WBE660S firmware versions through 6.70(ACGG.2) could allow an authenticated user with limited privileges to escalate their privileges to that of an administrator, enabling them to upload configuration files to a vulnerable device.

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 buffer overflow vulnerability in the parameter "action" of the CGI program in Zyxel VMG3625-T50B firmware versions through V5.50(ABPM.9.2)C0 could allow an authenticated attacker with administrator privileges to cause a temporary denial of service (DoS) condition against the web management interface by sending a crafted HTTP GET request to a vulnerable device if the function ZyEE is enabled.

A buffer overflow vulnerability in the packet parser of the third-party library "libclinkc" in Zyxel VMG8825-T50K firmware versions through V5.50(ABOM.8.4)C0 could allow an attacker to cause a temporary denial of service (DoS) condition against the web management interface by sending a crafted HTTP POST request to a vulnerable device.

CVE-2024-11667 is a directory traversal vulnerability (CWE-22) in the web management interface of several Zyxel firewall lines, allowing an unauthenticated remote attacker to download or upload files via a crafted URL. It is triggered over the network with no privileges or user interaction required, earning a critical CVSS 3.1 score of 9.8. Successful exploitation can expose sensitive files on the device and support broader intrusions, and CISA notes the flaw is being used in ransomware campaigns. Organizations running Zyxel ATP or USG FLEX firewalls on firmware V5.00–V5.38, or USG FLEX 50(W)/USG20(W)-VPN firewalls on V5.10–V5.38, are affected, particularly where the management interface is reachable from the internet. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2024-12-03 with known ransomware use; no public proof-of-concept is known.

Do: Upgrade affected ATP, USG FLEX, USG FLEX 50(W), and USG20(W)-VPN firewalls to a fixed firmware release per Zyxel's security advisory (any version above the affected V5.00–V5.38 / V5.10–V5.38 ranges); per CISA's KEV required action, apply the vendor's mitigations or discontinue use if mitigations are unavailable. Until patched, restrict or disable WAN-side HTTP/HTTPS management access to these devices and prioritize internet-exposed units. Given known ransomware use, hunt for signs of compromise on exposed devices, including unexpected uploaded files or anomalous administrative traffic.

**UNSUPPORTED WHEN ASSIGNED** The improper authentication vulnerability in the Zyxel P-6101C ADSL modem firmware version P-6101CSA6AP_20140331 could allow an unauthenticated attacker to read some device information via a crafted HTTP HEAD method.

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.

The insufficiently protected credentials vulnerability in the CLI command of the USG FLEX H series uOS firmware version V1.21 and earlier versions could allow an authenticated local attacker to gain privilege escalation by stealing the authentication token of a login administrator. Note that this attack could be successful only if the administrator has not logged out.

An improper restriction of operations within the bounds of a memory buffer in the USB file-sharing handler of the Zyxel VMG8825-T50K firmware versions through 5.50(ABOM.8)C0 could allow an authenticated attacker with administrator privileges to cause potential memory corruptions, resulting in a thread crash on an affected device.

An improper restriction of operations within the bounds of a memory buffer in the parameter type parser of the Zyxel VMG8825-T50K firmware versions through 5.50(ABOM.8)C0 could allow an authenticated attacker with administrator privileges to cause potential memory corruptions, resulting in a thread crash on an affected device.

**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.

An insufficient entropy vulnerability caused by the improper use of a randomness function with low entropy for web authentication tokens generation exists in the Zyxel GS1900-10HP firmware version V2.80(AAZI.0)C0. This vulnerability could allow a LAN-based attacker a slight chance to gain a valid session token if multiple authenticated sessions are alive.

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.

A buffer overflow vulnerability in the library "libclinkc" of the Zyxel VMG8825-T50K firmware version 5.50(ABOM.8)C0 could allow an unauthenticated attacker to cause denial of service (DoS) conditions by sending a crafted HTTP request to a vulnerable device.