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
- 7.2 High severity
ZyWALL/USG series firmware: Improper Neutralization of Special Elements used in an OS Command
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 firmwar
- 8.2 High severity
GS1920-24v2 firmware: Improper Check for Unusual or Exceptional Conditions
An improper check for unusual or exceptional conditions in the HTTP request processing function of Zyxel GS1920-24v2 firmware prior to V4.70(ABMH.8)C0, which could allow an unauthenticated attacker to corrupt the contents of the memory and result in a denial-o
- 8.8 High severity
NR7101 firmware: Improper Neutralization of Special Elements used in an OS Command
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.
- 9.8 Critical severity
NR7101 firmware: Buffer Copy without Checking Size of Input
A buffer overflow vulnerability in the library of the web server in Zyxel NR7101 firmware prior to V1.15(ACCC.3)C0, which could allow an unauthenticated attacker to execute some OS commands or to cause denial-of-service (DoS) conditions on a vulnerable device.
- 9.8 Critical severity
NBG7510 firmware: Improper Access Control
A DNS misconfiguration was found in Zyxel NBG7510 firmware versions prior to V1.00(ABZY.3)C0, which could allow an unauthenticated attacker to access the DNS server when the device is switched to the AP mode.
- 9.8 Critical severity
LTE3301-M209: Use of Hard-coded Credentials
A flaw in the Zyxel LTE3301-M209 firmware verisons prior to V1.00(ABLG.6)C0 could allow a remote attacker to access the device using an improper pre-configured password if the remote administration feature has been enabled by an authenticated administrator.
- 9.8 Critical severity
Zyxel NAS326 firmware: Use of Externally-Controlled Format String
A format string vulnerability in Zyxel NAS326 firmware versions prior to V5.21(AAZF.12)C0 could allow an attacker to achieve unauthorized remote code execution via a crafted UDP packet.
- 7.8 High severity
USG FLEX 100(W) firmware: Improper Privilege Management
A privilege escalation vulnerability was identified in the CLI command of Zyxel USG FLEX 100(W) firmware versions 4.50 through 5.30, USG FLEX 200 firmware versions 4.50 through 5.30, USG FLEX 500 firmware versions 4.50 through 5.30, USG FLEX 700 firmware versi
- 7.8 High severity
USG/ZyWALL series firmware: Improper Neutralization of Special Elements used in an OS Command
A argument injection vulnerability in the 'packet-trace' CLI command of Zyxel USG/ZyWALL series firmware versions 4.09 through 4.71, USG FLEX series firmware versions 4.50 through 5.21, ATP series firmware versions 4.32 through 5.21, VPN series firmware versio
- 7.8 High severity
Multiple improper input validation flaws were identified in some CLI commands of Zyxel…
Multiple improper input validation flaws were identified in some CLI commands of Zyxel USG/ZyWALL series firmware versions 4.09 through 4.71, USG FLEX series firmware versions 4.50 through 5.21, ATP series firmware versions 4.32 through 5.21, VPN series firmwa
- 9.8 Critical severity
Zyxel Multiple Firewalls OS Command Injection Exploited
A OS command injection vulnerability in the CGI program of Zyxel USG FLEX 100(W) firmware versions 5.00 through 5.21 Patch 1, USG FLEX 200 firmware versions 5.00 through 5.21 Patch 1, USG FLEX 500 firmware versions 5.00 through 5.21 Patch 1, USG FLEX 700 firmw
- 8.0 High severity
VMG3312-T20A firmware: Improper Neutralization of Special Elements used in an OS Command
A command injection vulnerability in the CGI program of Zyxel VMG3312-T20A firmware version 5.30(ABFX.5)C0 could allow a local authenticated attacker to execute arbitrary OS commands on a vulnerable device via a LAN interface.
- 7.8 High severity
Zyxel AP Configurator (ZAC): Incorrect Permission Assignment for Critical Resource
A local privilege escalation vulnerability caused by incorrect permission assignment in some directories of the Zyxel AP Configurator (ZAC) version 1.1.4, which could allow an attacker to execute arbitrary code as a local administrator.
- 9.8 Critical severity
USG/ZyWALL series firmware: Improper Authentication
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 thr
- 9.8 Critical severity
Zyxel Multiple Products Use of Hard-Coded Credentials Exploited
Firmware version 4.60 of Zyxel USG devices contains an undocumented account (zyfwp) with an unchangeable password. The password for this account can be found in cleartext in the firmware. This account can be used by someone to login to the ssh server or web in
- 9.8 Critical severity
Zyxel Multiple NAS Devices OS Command Injection Exploited
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 dev
- 9.8 Critical severity
Zyxel P660HN-T1A Routers Command Injection Exploited
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
- 8.8 High severity
Zyxel EMG2926 Routers Command Injection Exploited
A command injection vulnerability was discovered on the Zyxel EMG2926 home router with firmware V1.00(AAQT.4)b8. The vulnerability is located in the diagnostic tools, specifically the nslookup function. A malicious user may exploit numerous vectors to execute