What is CVE-2026-7273?
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.
Timeline
- 2026-06-16Published to the U.S. National Vulnerability Database (NVD)
- 2026-09-21Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
- 2026-09-23First covered in a defend.network daily briefing
- 2026-09-24CISA federal remediation deadline (BOD 22-01)
- 2026-10-25NVD record last updated
CISA Known Exploited Vulnerability
Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
Affected product
Zyxel GS1900 Series Switches
NVD also lists CPE entries for: Zyxel Gs1900-8 Firmware, Zyxel Gs1900-8, Zyxel Gs1900-8hp Firmware, Zyxel Gs1900-8hp, Zyxel Gs1900-10hp Firmware
Remediation Steps
- Apply the vendor security update for Zyxel GS1900 Series Switches as a priority.
- Restrict network exposure of the affected service to trusted sources until patched.
- Review logs and detections for indicators of exploitation.
- Confirm fixed versions against the official vendor advisory before deploying.
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
- 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
- https://nvd.nist.gov/vuln/detail/CVE-2026-7273
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Referenced in our briefings & reports
- Vulnerability Priority Report – Week 1 of November 2026 (November 2 – 8)
- Vulnerability Priority Report – Week 3 of October 2026 (October 19 – 25)
- Vulnerability Priority Report – Week 2 of October 2026 (October 12 – 18)
- Vulnerability Priority Report – Week 1 of October 2026 (October 5 – 11)
- Vulnerability Priority Report – Week 4 of September 2026 (September 28 – October 4)
- Vulnerability Priority Report – Week 3 of September 2026 (September 21 – 27)
- APT flaw, Rails RCE, Zyxel zero-days, Debian/Ubuntu patch urgency (2026-11-05)
- Check Point, WordPress, Zyxel actively exploited; EvilTokens phishing infrastructure seized (2026-09-23)
Related vulnerabilities
- CVE-2026-53921 (same weakness: CWE-121)
- CVE-2021-27137 – Dd-Wrt (same weakness: CWE-121)
- CVE-2026-41089 – Microsoft Windows Server (same weakness: CWE-121)
- CVE-2025-53521 – F5 BIG-IP (same weakness: CWE-121)
Browse all tracked CVEs in the defend.network CVE database →
🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.