Zyxel: security record
CISA's Known Exploited Vulnerabilities catalog lists 7 flaws in Zyxel routers and network gear and home storage and media servers that attackers have exploited in the wild, added between 25 March 2022 and 21 September 2026. CISA marks 1 as known to have been used in ransomware campaigns.
What this list means
CISA adds a flaw to its Known Exploited Vulnerabilities catalog when there is reliable evidence that attackers have used it in the wild and clear steps exist to fix or reduce it. A listed flaw usually has a patch or workaround from the maker. Some older devices are no longer supported and will not be fixed. If you own an affected model, check the maker's notice, update the firmware or replace the device if it is out of support.
Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
Zyxel GS1900 series switches contain a stack-based buffer overflow vulnerability in the CGI program which could allow a LAN-based, unauthenticated attacker to exploit the flaw and potentially execute OS commands via a crafted HTTP request.
Zyxel DSL CPE OS Command Injection Vulnerability
Multiple Zyxel DSL CPE devices contain a post-authentication command injection vulnerability in the management commands that could allow an authenticated attacker to execute OS commands via Telnet.
Zyxel DSL CPE OS Command Injection Vulnerability
Multiple Zyxel DSL CPE devices contain a post-authentication command injection vulnerability in the CGI program that could allow an authenticated attacker to execute OS commands via a crafted HTTP request.
Zyxel EMG2926 Routers Command Injection Vulnerability
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 ping_ip parameter to the expert/maintenance/diagnostic/nslookup URI.
Zyxel P660HN-T1A Routers Command Injection Vulnerability
Zyxel P660HN-T1A routers contain a command injection vulnerability in the Remote System Log forwarding function, which is accessible by an unauthenticated user and exploited via the remote_host parameter of the ViewLog.asp page.
Zyxel Multiple NAS Devices Command Injection Vulnerability
Multiple Zyxel network-attached storage (NAS) devices contain a pre-authentication command injection vulnerability that could allow an unauthenticated attacker to execute commands remotely via a crafted HTTP request.
Zyxel Multiple NAS Devices OS Command Injection Vulnerability
Multiple Zyxel network-attached storage (NAS) devices contain a pre-authentication command injection vulnerability, which may allow a remote, unauthenticated attacker to execute arbitrary code.
A listing shows that a flaw was exploited, not how a maker compares overall. Makers with many devices in use tend to appear more often. Check the maker's own notice for the models and firmware versions affected.
Sources
- Cybersecurity and Infrastructure Security Agency (CISA), Known Exploited Vulnerabilities Catalog, version 2026.10.28, released 28 October 2026
- National Institute of Standards and Technology, National Vulnerability Database
Checked 29 October 2026.