CVE-2026-7273 Zyxel GS1900 Series Switches: memory-safety flaw
In plain words: The program mishandles the memory it uses to keep track of data. A specially made input can scramble that memory. Usually lets an attacker crash the program or run their own code with its permissions.
Confirmed exploited by CISA on · US federal patch deadline Sep 24, 2026
What to do
- Install Zyxel's security update for GS1900 Series Switches. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Turn on automatic firmware updates and replace gear the maker no longer supports.
- Change default passwords and switch off remote administration and features you do not use.
- Do not put storage boxes or cameras directly on the internet — use the maker's app or a VPN.
Who is affected
Could reach you. This one is aimed at devices or apps of the kind people own.
What's at risk: Taken over in bulk to join botnets, used to watch your traffic, or — for storage boxes — locked by ransomware.
The details
- Official name
- Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
- Product
- Zyxel GS1900 Series Switches
- CISA description
- 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.
- Type of flaw
- Memory-safety flaw (CWE-121)
- Confirmed exploited
- Sep 21, 2026
- US federal patch deadline
- Sep 24, 2026
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Answering about CVE-2026-7273 ·
Questions about CVE-2026-7273
Is CVE-2026-7273 being exploited?
Yes. CISA added CVE-2026-7273 to its Known Exploited Vulnerabilities catalog on Sep 21, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2026-7273?
Install Zyxel's security update for GS1900 Series Switches. If no update exists, follow the vendor's workaround or stop using the product until one ships. Turn on automatic firmware updates and replace gear the maker no longer supports.
Am I affected by CVE-2026-7273?
Only if you use Zyxel GS1900 Series Switches. This one is aimed at devices or apps of the kind people own.