NetSight
high8.8Known exploited

CVE-2026-7273

Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability

Exploited in the wild

This vulnerability is on the CISA Known Exploited Vulnerabilities list, added 2026-09-21. Federal due date: 2026-09-24.

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.

Impact

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.

Affected products

VendorProductAffected versions
ZyxelGS1900-24EP Firmware
Version ≤ 2.90(ABTO.1)C0
ZyxelGS1900-24HPv2 Firmware
Version ≤ 2.90(ABTP.1)C0
ZyxelGS1900-16 Firmware
Version ≤ 2.90(AAHJ.1)C0
ZyxelGS1900-8HP Firmware
Version ≤ 2.90(AAHI.1)C0
ZyxelGS1900-48HPv2 Firmware
Version ≤ 2.90(ABTQ.1)C0
ZyxelGS1900-24E Firmware
Version ≤ 2.90(AAHK.1)C0
ZyxelGS1900-24 Firmware
Version ≤ 2.90(AAHL.1)C0
ZyxelGS1900-48 Firmware
Version ≤ 2.90(AAHN.1)C0
ZyxelGS1900-8 Firmware
Version ≤ 2.90(AAHH.1)C0
ZyxelGS1900-10HP Firmware
Version ≤ 2.90(AAZI.1)C0
ZyxelGs1900-8 Firmware
before 2.90\(aahh.2\)c0
ZyxelGs1900-8hp Firmware
before 2.90\(aahi.2\)c0
ZyxelGs1900-10hp Firmware
before 2.90\(aazi.2\)c0
ZyxelGs1900-16 Firmware
before 2.90\(aahj.2\)c0
ZyxelGs1900-24 Firmware
before 2.90\(aahl.2\)c0
ZyxelGs1900-24e Firmware
before 2.90\(aahk.2\)c0
ZyxelGs1900-24ep Firmware
before 2.90\(abto.2\)c0
ZyxelGs1900-24hpv2 Firmware
before 2.90\(abtp.2\)c0
ZyxelGs1900-48 Firmware
before 2.90\(aahn.2\)c0
ZyxelGs1900-48hpv2 Firmware
before 2.90\(abtq.2\)c0

Weakness classification

References