MajorExploited now Active exploitation

CVE-2026-7273: Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability

CISA KEV · officialPublished Sep 21, 2026Risk 77/100

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. Vendor: Zyxel — GS1900 Series Switches 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. Due: 2026-09-24

Recommended 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.

CISA remediation due: 2026-09-24

Technical details

Vendor: Zyxel
Product: GS1900 Series Switches
Exploitation: active
Evidence: official

Evidence and sources

This record is attributed to CISA KEV. Exploitation status and remediation guidance are kept separate from the vulnerability's technical severity.

Open primary source