# Zyxel GS1900 switches buffer overflow actively exploited

Published: 2026-09-21 · Severity: severe · Sectors: government-national, infrastructure
Canonical: https://vorant.io/reports/ba3ddc02-c0a1-5d1c-b71c-3dd37b133873/zyxel-gs1900-switches-buffer-overflow-actively-exploited

> Stack-based buffer overflow in Zyxel GS1900 Series switches is actively exploited in the wild; patch immediately.

CISA has added CVE-2026-7273 to its Known Exploited Vulnerabilities Catalog, confirming active exploitation of a stack-based buffer overflow vulnerability in Zyxel GS1900 Series network switches. The vulnerability allows attackers to achieve total control of affected devices post-exploitation, making it a critical priority for remediation. This vulnerability is particularly significant for federal civilian agencies under BOD 26-04, which mandates rapid patching of KEV Catalog vulnerabilities on publicly exposed assets. The vulnerability poses substantial risk to network infrastructure, as switches are often foundational components in organizational networks. Organizations are advised to prioritize immediate patching and to assess whether affected systems were compromised prior to patch deployment.

## Mentioned in this report

- Vulnerabilities: CVE-2026-7273 (KEV)

Source reporting: https://www.cisa.gov/news-events/alerts/2026/09/21/cisa-adds-one-known-exploited-vulnerability-catalog

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