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Home - Vulnerability NotesPrint
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CERT-In Vulnerability Note CIVN-2026-0477
Buffer Overflow Vulnerability in Zyxel

Original Issue Date:September 28, 2026

Severity Rating: HIGH

Software Affected

  • Zyxel GS1900-8 firmware version 2.90(AAHH.1)C0 and earlier
  • Zyxel GS1900-8HP firmware version 2.90(AAHI.1)C0 and earlier
  • Zyxel GS1900-10HP firmware version 2.90(AAZI.1)C0 and earlier
  • Zyxel GS1900-16 firmware version 2.90(AAHJ.1)C0 and earlier
  • Zyxel GS1900-24 firmware version 2.90(AAHL.1)C0 and earlier
  • Zyxel GS1900-24E firmware version 2.90(AAHK.1)C0 and earlier
  • Zyxel GS1900-24EP firmware version 2.90(ABTO.1)C0 and earlier
  • Zyxel GS1900-24HPv2 firmware version 2.90(ABTP.1)C0 and earlier
  • Zyxel GS1900-48 firmware version 2.90(AAHN.1)C0 and earlier
  • Zyxel GS1900-48HPv2 firmware version 2.90(ABTQ.1)C0 and earlier

Overview

A stack-based buffer overflow vulnerability has been reported in the CGI program of Zyxel GS1900 series switch firmware which could allow an unauthenticated attacker with LAN level access to execute OS commands on affected device.

Target Audience:
Organizations and network administrators using affected Zyxel products.

Risk Assessment:
High risk of unauthorized OS command execution, potential compromise of affected network switches and disruption of network operations.

Impact Assessment:
Potential for OS command execution and compromise of affected network switches, with possible impact to confidentiality, integrity, and availability.

Description

Zyxel GS1900 series switches are network switching devices designed to provide wired network connectivity and network management capabilities for organizational networks.

This vulnerability exists in Zyxel products due to stack-based buffer overflow in CGI program of its GS1900 series switch firmware. A LAN-based, unauthenticated attacker could exploit this vulnerability by sending a specially crafted HTTP request.

Successful exploitation of this vulnerability could allow an unauthenticated attacker with LAN level access to execute OS commands on affected device.

Solution

Apply appropriate security updates and mitigations as recommended by the vendor.
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026

Vendor Information

Zyxel Networks
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026

References

 
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026

CVE Name
CVE-2026-7273

Disclaimer

The information provided herein is on "as is" basis, without warranty of any kind.

Contact Information

Email: info@cert-in.org.in
Phone: +91-11-22902657

Postal address

Indian Computer Emergency Response Team (CERT-In)
Ministry of Electronics and Information Technology
Government of India
Electronics Niketan
6, CGO Complex, Lodhi Road,
New Delhi - 110 003
India

 
Indian Computer Emergency Response Team - CERT-In, Ministry of Electronics and Information Technology, Government of India.
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