Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run GS1900 Series Switches, fix it now.
CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
US federal civilian agencies must remediate by Sep 24, 2026.
No official fix confirmed yet
Until a fix ships, follow the vendor's mitigations and CISA's required action, limit exposure of affected systems, and watch this record for a patch.
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.
Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.
| Product | Vendor | Source |
|---|---|---|
| GS1900 Series Switches | Zyxel | KEV |
Sources: KEV = CISA Known Exploited Vulnerabilities catalog. Version details have not been published yet.
Developments from the last 30 days, newest first.
CVE-2026-7273 scored CVSS 8.8: Zyxel GS1900 Series Switches, Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
CISA lists this as exploited in the wild. Unpatched GS1900 Series Switches systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
CVE-2026-7273 added to CISA KEV: Zyxel GS1900 Series Switches, Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
CISA lists this as exploited in the wild. Unpatched GS1900 Series Switches systems are exposed to active attacks now.
Basis: CISA Known Exploited Vulnerabilities catalog
CISA lists this as exploited in the wild. Unpatched BIG-IP and Multiple Products systems are exposed to active attacks now.
Treat this as an emergency.
CISA lists this as exploited in the wild. Unpatched GS1900 Series Switches systems are exposed to active attacks now.
Apply the vendor's security update for GS1900 Series Switches.
