Zyxel GS1900-48HPv2 2.90(ABTQ.1)C0 Buffer Overflow in CGI Program
CVE-2026-7273 Published on June 16, 2026
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.
Known Exploited Vulnerability
This Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. 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.
The following remediation steps are recommended / required by September 24, 2026: 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 applicab
Vulnerability Analysis
Weakness Type
What is a Stack Overflow Vulnerability?
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
CVE-2026-7273 has been classified to as a Stack Overflow vulnerability or weakness.
Affected Versions
Zyxel GS1900-48HPv2 firmware:- Version <= 2.90(ABTQ.1)C0 is affected.
- Version <= 2.90(AAHH.1)C0 is affected.
- Version <= 2.90(AAHI.1)C0 is affected.
- Version <= 2.90(AAZI.1)C0 is affected.
- Version <= 2.90(AAHJ.1)C0 is affected.
- Version <= 2.90(AAHL.1)C0 is affected.
- Version <= 2.90(AAHK.1)C0 is affected.
- Version <= 2.90(ABTO.1)C0 is affected.
- Version <= 2.90(ABTP.1)C0 is affected.
- Version <= 2.90(AAHN.1)C0 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.