An out-of-bounds write vulnerability in the CGI program of Zyxel GS1900-24E firmware versions through 2.90(AAHK.2)C0 could allow an unauthenticated adjacent attacker to exploit the flaw and potentially execute OS commands via a crafted HTTP request.

A buffer overflow vulnerability in the zdpwtp binary in Zyxel NWA110AX firmware versions through 7.12(ABTG.0)C0 could allow a LAN-based attacker to escalate privileges on an affected device.

An incorrect authorization vulnerability in the Data Access Layer (DAL) of Zyxel EX3501-T0 firmware versions through 5.44(ACHR.6)C0 could allow an authenticated attacker to escalate privileges by modifying the loginprivilege data on an affected device.

UNSUPPORTED WHEN ASSIGNED The command injection vulnerability in the CGI program "remotehelp-cgi" in Zyxel NAS326 firmware versions before V5.21(AAZF.17)C0 and NAS542 firmware versions before V5.21(ABAG.14)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted HTTP POST request.

Chromium: CVE-2023-6347 Use after free in Mojo

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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 stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions through 2.90(ABTQ.1)C0 could allow a LAN-based, unauthenticated attacker to exploit the flaw and potentially execute OS commands via a crafted HTTP request.

An improper authentication vulnerability in the "sociallogin.cgi" CGI program in Zyxel WAX650S firmware versions through 7.10(ABRM.4)C0 could allow an attacker on the WLAN to bypass captive portal authentication.

A post-authentication command injection vulnerability in the "export-cgi" CGI program in Zyxel WAX650S firmware versions through 7.10(ABRM.4)C0 could allow an authenticated attacker with administrator privileges to execute OS commands on an affected device.

Insufficiently Protected Credentials vulnerability in Zyxel Networks WAH7601 allows Retrieve Embedded Sensitive Data.

This issue affects WAH7601: through 20072026.

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

Zyxel EMG2926 routers contain a command injection vulnerability located in the diagnostic tools, specifically the nslookup function. A malicious user may exploit numerous vectors to execute malicious commands on the router, such as the pingip parameter to the expert/maintenance/diagnostic/nslookup URI.

The flaw is a stack-based CGI overflow that could allow unauthenticated OS command execution from the LAN. Federal agencies have until Sept. 24 to address it. Another reminder that edge switches can quickly become high-value targets once active exploitation starts.

I published my technical write-up for CVE-2026-8508, a pre-authentication trust-boundary flaw in Zyxel's guest Wi-Fi social-login flow.

The analysis is based on the WAX650S, while Zyxel's advisory expanded the affected scope to 39 models (APs, FWA7 units, and a security router). The post includes root cause, affected versions, remediation, and the reproduction environment.

Technical analysis of CVE-2026-6837, an authenticated command-injection vulnerability in Zyxel’s PKCS#12 certificate export flow.

The post covers the vulnerable execution path, root cause, affected firmware scope, and the firmware-emulation methodology used during analysis.

I published my technical write-up for CVE-2026-6837, an authenticated command-injection issue in Zyxel’s certificate export functionality.

The analysis is based on the WAX650S, while Zyxel’s advisory expanded the affected scope to 18 AP models. The post includes root cause, affected versions, remediation, and the reproduction environment.

A directory traversal vulnerability in the web management interface of Zyxel ATP series firmware versions V5.00 through V5.38, USG FLEX series firmware versions V5.00 through V5.38, USG FLEX 50(W) series firmware versions V5.10 through V5.38, and USG20(W)-VPN series firmware versions V5.10 through V5.38 could allow an attacker to download or upload files via a crafted URL.

A path traversal vulnerability in the CLI command used to execute configuration files in Zyxel ATP series firmware versions from V4.32 through V5.42 Patch 1, USG FLEX series firmware versions from V4.50 through V5.42 Patch 1, USG FLEX 50(W) series firmware versions from V4.16 through V5.42 Patch 1, and USG20(W)-VPN series firmware versions from V4.16 through V5.42 Patch 1 could allow an authenticated attacker with administrator privileges to execute a crafted malicious configuration file 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.

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 missing authorization vulnerability in Zyxel GS1200-5v3 firmware versions through 1.00(ACPS.2)C0, GS1200-8v3 firmware versions through 1.00(ACPT.2)C0,  GS1200-5HPv3 firmware versions through 1.00(ACPU.2)C0, GS1200-8HPv3 firmware versions through 1.00(ACPV.2)C0, and GS1200-10v3 firmware versions through 1.00(ACPW.2)C0 could allow a LAN-based, unauthenticated attacker to read the system configuration from a log file via a crafted HTTP request.

A buffer overflow vulnerability in the UPnP AddPortMapping() command in Zyxel VMG4005-B50B firmware versions through 5.13(ABRL.5.4)C0 could allow an adjacent attacker to trigger a temporary denial-of-service (DoS) condition affecting the UPnP function of the affected device.

A buffer overflow vulnerability in the UPnP DeletePortMapping() command in Zyxel VMG4005-B50B firmware versions through 5.13(ABRL.5.4)C0 could allow an adjacent attacker to trigger a temporary denial-of-service (DoS) condition affecting the UPnP function of the affected device.

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.

UNSUPPORTED WHEN ASSIGNED An improper restriction of excessive authentication attempts vulnerability in the web management interface of Zyxel WRE6505 v2 firmware version V1.00(ABDV.3)C0 could allow an adjacent attacker on the LAN to brute-force the password and bypass authentication.

UNSUPPORTED WHEN ASSIGNED An insecure storage of sensitive information vulnerability in the configuration file of Zyxel WRE6505 v2 firmware version V1.00(ABDV.3)C0 could allow a local attacker with administrator privileges to download and decrypt a backup configuration file.

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.