Actively exploited · Published Jun 16, 2026 · Assigned by Zyxel
CVE-2026-7273
High 8.8 Exploited
In plain English
A high-severity stack buffer overflow in GS1900-10HP firmware from Zyxel. Attackers are actively exploiting it in the wild (listed by CISA on September 21, 2026). The chance it is exploited in the next 30 days is estimated at 2.7% (higher than 86% of all known vulnerabilities). 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.
CISA guidance
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.
Federal agencies must remediate by Sep 24, 2026.
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Zyxel | GS1900-48HPv2 firmware | <= 2.90(ABTQ.1)C0 |
| Zyxel | GS1900-8 firmware | <= 2.90(AAHH.1)C0 |
| Zyxel | GS1900-8HP firmware | <= 2.90(AAHI.1)C0 |
| Zyxel | GS1900-10HP firmware | <= 2.90(AAZI.1)C0 |
| Zyxel | GS1900-16 firmware | <= 2.90(AAHJ.1)C0 |
| Zyxel | GS1900-24 firmware | <= 2.90(AAHL.1)C0 |
| Zyxel | GS1900-24E firmware | <= 2.90(AAHK.1)C0 |
| Zyxel | GS1900-24EP firmware | <= 2.90(ABTO.1)C0 |
| Zyxel | GS1900-24HPv2 firmware | <= 2.90(ABTP.1)C0 |
| Zyxel | GS1900-48 firmware | <= 2.90(AAHN.1)C0 |
Weakness: CWE-121 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 vendor-advisory
- https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273 government-resource