All vulnerabilities
CVE-2026-7273

Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability

Zyxel GS1900 Series SwitchesNetwork & edge
Open in ThreatlineRecord JSON
CVSS
8.8High
ExploitationExploited in the wildAdded to KEV 21 Sep 2026CISA KEV
Exploit odds (EPSS)2.50%Chance of exploitation activity in the next 30 days, higher than 84% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed inNone listedNo source names a fixed version. Check the vendor advisory below
Federal deadline24 Sep 2026Remediation due date for US federal agenciesCISA KEV
CISA required actionApply 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 KEV
Patching is not enoughCISA requires federal agencies to look for signs of compromise on affected systems, not only patch (forensic triage under BOD 26-04). Treat exposed systems as possibly compromised. CISA guidance

What fixes it

No source in this snapshot names a fixed version. The vendor advisories under References are the place to check.

Timeline

  1. 16 Jun 2026, 02:20 UTCPublishedCVE List
  2. 21 Sep 2026Added to CISA KEVCISA KEV

Reports 1

1 outlet mention it. Reports are not confirmation; each links to its source.

Description

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.

Text from CVE List

Affected versions 10

  • GS1900-48HPv2 firmwareaffected: <= 2.90(ABTQ.1)C0CVE List
  • GS1900-8 firmwareaffected: <= 2.90(AAHH.1)C0CVE List
  • GS1900-8HP firmwareaffected: <= 2.90(AAHI.1)C0CVE List
  • GS1900-10HP firmwareaffected: <= 2.90(AAZI.1)C0CVE List
  • GS1900-16 firmwareaffected: <= 2.90(AAHJ.1)C0CVE List
  • GS1900-24 firmwareaffected: <= 2.90(AAHL.1)C0CVE List
  • GS1900-24E firmwareaffected: <= 2.90(AAHK.1)C0CVE List
  • GS1900-24EP firmwareaffected: <= 2.90(ABTO.1)C0CVE List
  • GS1900-24HPv2 firmwareaffected: <= 2.90(ABTP.1)C0CVE List
  • GS1900-48 firmwareaffected: <= 2.90(AAHN.1)C0CVE List

References 4