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
| Vendor | Product | Affected versions |
|---|---|---|
| Zyxel | GS1900-24EP Firmware | Version ≤ 2.90(ABTO.1)C0 |
| Zyxel | GS1900-24HPv2 Firmware | Version ≤ 2.90(ABTP.1)C0 |
| Zyxel | GS1900-16 Firmware | Version ≤ 2.90(AAHJ.1)C0 |
| Zyxel | GS1900-8HP Firmware | Version ≤ 2.90(AAHI.1)C0 |
| Zyxel | GS1900-48HPv2 Firmware | Version ≤ 2.90(ABTQ.1)C0 |
| Zyxel | GS1900-24E Firmware | Version ≤ 2.90(AAHK.1)C0 |
| Zyxel | GS1900-24 Firmware | Version ≤ 2.90(AAHL.1)C0 |
| Zyxel | GS1900-48 Firmware | Version ≤ 2.90(AAHN.1)C0 |
| Zyxel | GS1900-8 Firmware | Version ≤ 2.90(AAHH.1)C0 |
| Zyxel | GS1900-10HP Firmware | Version ≤ 2.90(AAZI.1)C0 |
| Zyxel | Gs1900-8 Firmware | before 2.90\(aahh.2\)c0 |
| Zyxel | Gs1900-8hp Firmware | before 2.90\(aahi.2\)c0 |
| Zyxel | Gs1900-10hp Firmware | before 2.90\(aazi.2\)c0 |
| Zyxel | Gs1900-16 Firmware | before 2.90\(aahj.2\)c0 |
| Zyxel | Gs1900-24 Firmware | before 2.90\(aahl.2\)c0 |
| Zyxel | Gs1900-24e Firmware | before 2.90\(aahk.2\)c0 |
| Zyxel | Gs1900-24ep Firmware | before 2.90\(abto.2\)c0 |
| Zyxel | Gs1900-24hpv2 Firmware | before 2.90\(abtp.2\)c0 |
| Zyxel | Gs1900-48 Firmware | before 2.90\(aahn.2\)c0 |
| Zyxel | Gs1900-48hpv2 Firmware | before 2.90\(abtq.2\)c0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- CISA KEV catalog
- 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
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273
- https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation