Zyxel vulnerabilities
We track 98 vulnerabilities in Zyxel products across 60+ products. 98 are rated high or critical, and 13 have been exploited in real attacks. The most recent was published on November 3, 2026.
Latest Zyxel vulnerabilities
- 9.8 Critical severity
NWA1100-N firmware: Improper Neutralization of Special Elements used in an OS Command
** 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
- 9.8 Critical severity
NAS326 firmware: Unrestricted Upload of File with Dangerous Type
** UNSUPPORTED WHEN ASSIGNED ** The remote code execution vulnerability in the CGI program “file_upload-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
- 9.8 Critical severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the “setCookie” parameter 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 s
- 9.8 Critical severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
** UNSUPPORTED WHEN ASSIGNED ** The command injection vulnerability in the CGI program "remote_help-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 e
- 8.1 High severity
ATP series firmware: Use of Externally-Controlled Format String
A format string vulnerability in a function of the IPSec VPN feature in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from 4.16 throu
- 7.2 High severity
ATP series firmware: Improper Neutralization of Special Elements used in an OS Command
A post-authentication command injection vulnerability in the file upload binary in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from
- 7.2 High severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
The post-authentication command injection vulnerability in Zyxel NAS326 firmware versions through V5.21(AAZF.15)C0 and NAS542 firmware versions through V5.21(ABAG.12)C0 could allow an authenticated attacker with administrator privileges to execute some operati
- 9.8 Critical severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
The improper neutralization of special elements in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by send
- 9.8 Critical severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
A command injection vulnerability in the web server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) commands by sending a crafted U
- 8.8 High severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
A post-authentication command injection vulnerability in the WSGI server of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an authenticated attacker to execute some operating system (OS) commands by
- 8.8 High severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
The improper neutralization of special elements in the CGI program of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an authenticated attacker to execute some operating system (OS) commands by sendin
- 9.8 Critical severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
A command injection vulnerability in the “show_zysync_server_contents” function of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to execute some operating system (OS) com
- 7.5 High severity
NAS326 firmware: Improper Authentication
An improper authentication vulnerability in the authentication module of the Zyxel NAS326 firmware version V5.21(AAZF.14)C0 and NAS542 firmware version V5.21(ABAG.11)C0 could allow an unauthenticated attacker to obtain system information by sending a crafted U
- 7.5 High severity
ATP series firmware: Integer Overflow or Wraparound
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
- 7.8 High severity
SecuExtender SSL VPN Client: Out-of-bounds Write
The out-of-bounds write vulnerability in the Windows-based SecuExtender SSL VPN Client software version 4.0.4.0 could allow an authenticated local user to gain a privilege escalation by sending a crafted CREATE message.
- 7.5 High severity
PMG2005-T20B: Buffer Copy without Checking Size of Input
** UNSUPPORTED WHEN ASSIGNED **The buffer overflow vulnerability in the Zyxel PMG2005-T20B firmware version V1.00(ABNK.2)b11_C0 could allow an unauthenticated attacker to cause a denial of service condition via a crafted uid.
- 8.8 High severity
NBG6604 firmware: Improper Neutralization of Special Elements used in an OS Command
A post-authentication command injection vulnerability in the NTP feature of Zyxel NBG6604 firmware version V1.01(ABIR.1)C0 could allow an authenticated attacker to execute some OS commands remotely by sending a crafted HTTP request.
- 8.0 High severity
ATP series firmware: Improper Neutralization of Special Elements used in an OS 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
- 8.8 High severity
USG FLEX series firmware: Improper Neutralization of Special Elements used in an OS Command
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 e
- 8.0 High severity
ATP series firmware: Improper Neutralization of Special Elements used in an OS Command
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 Patc
- 8.8 High severity
ATP series firmware: Improper Neutralization of Special Elements used in an OS Command
A command injection vulnerability in the configuration parser of 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, U
- 8.8 High severity
ATP series firmware: Use of Externally-Controlled Format String
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 vers
- 8.8 High severity
ATP series firmware: Improper Neutralization of Special Elements used in an OS Command
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 fi
- 9.8 Critical severity
Zyxel Multiple NAS Devices Command Injection Exploited
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 at
- 7.2 High severity
NAS326 firmware: Improper Neutralization of Special Elements used in an OS Command
The post-authentication command injection vulnerability in the Zyxel NAS326 firmware versions prior to V5.21(AAZF.13)C0 could allow an authenticated attacker with administrator privileges to execute some operating system (OS) commands on an affected device rem
- 9.8 Critical severity
Zyxel Multiple Firewalls Buffer Overflow Exploited
A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN
- 9.8 Critical severity
Zyxel Multiple Firewalls Buffer Overflow Exploited
A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX series firmware versions 4.60 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.60 through 5.36 Patch 1, USG20(W)-VPN
- 7.5 High severity
NBG-418N v2 firmware: Buffer Copy without Checking Size of Input
A buffer overflow vulnerability in the Zyxel NBG-418N v2 firmware versions prior to V1.00(AARP.14)C0 could allow a remote unauthenticated attacker to cause DoS conditions by sending crafted packets if Telnet is enabled on a vulnerable device.
- 7.5 High severity
NBG-418N v2 firmware: Improper Neutralization of Input During Web Page Generation
A cross-site scripting (XSS) vulnerability in the Zyxel NBG-418N v2 firmware versions prior to V1.00(AARP.14)C0 could allow a remote authenticated attacker with administrator privileges to store malicious scripts using a web management interface parameter, res
- 8.8 High severity
NBG6604 firmware: Improper Neutralization of Special Elements used in an OS Command
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.
- 7.5 High severity
DX5401-B0 firmware: Exposure of Sensitive Information to an Unauthorized Actor
The sensitive information exposure vulnerability in the CGI “Export_Log” and the binary “zcmd” in Zyxel DX5401-B0 firmware versions prior to V5.17(ABYO.1)C0 could allow a remote unauthenticated attacker to read the system files and to retrieve the password of
- 9.8 Critical severity
DX5401-B0 firmware: Buffer Copy without Checking Size of Input
The buffer overflow vulnerability in the library “libclinkc.so” of the web server “zhttpd” in Zyxel DX5401-B0 firmware versions prior to V5.17(ABYO.1)C0 could allow a remote unauthenticated attacker to execute some OS commands or to cause denial-of-service (Do
- 9.8 Critical severity
Zyxel Multiple Firewalls OS Command Injection Exploited
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
- 8.8 High severity
ATP series firmware: Improper Neutralization of Special Elements used in an OS Command
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 v
- 7.5 High severity
ATP series firmware: Buffer Copy without Checking Size of Input
A buffer overflow vulnerability in the “sdwan_iface_ipc” binary of Zyxel ATP series firmware versions 5.10 through 5.32, USG FLEX series firmware versions 5.00 through 5.32, USG FLEX 50(W) firmware versions 5.10 through 5.32, USG20(W)-VPN firmware versions 5.1
- 8.1 High severity
The configuration parser of Zyxel ATP series firmware versions 5.10 through 5.35, USG FLEX…
The configuration parser of Zyxel ATP series firmware versions 5.10 through 5.35, USG FLEX series firmware versions 5.00 through 5.35, USG FLEX 50(W) firmware versions 5.10 through 5.35, USG20(W)-VPN firmware versions 5.10 through 5.35, and VPN series firmware
- 7.5 High severity
USG FLEX series firmware: Buffer Copy without Checking Size of Input
A buffer overflow vulnerability in the “fbwifi_forward.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.30 through 5.35, USG20(W)-VPN firmware versions 4.30 through 5.35, and VPN series firmware
- 7.2 High severity
USG FLEX series firmware: Improper Limitation of a Pathname to a Restricted Directory
A path traversal vulnerability in the “account_print.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote authenticated attacker with administrator privile
- 8.1 High severity
USG FLEX series firmware: Improper Neutralization of Special Elements used in a Command
A post-authentication command injection vulnerability in the “account_operator.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote authenticated attacker
- 9.8 Critical severity
LTE3316-M604: Improper Access Control
A security misconfiguration vulnerability exists in the Zyxel LTE3316-M604 firmware version V2.00(ABMP.6)C0 due to a factory default misconfiguration intended for testing purposes. A remote attacker could leverage this vulnerability to access an affected devic