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Known exploited vulnerability

CVE-2026-7273

highCVSS 3.1 8.8In CISA KEVEPSS 2.7%Published · Zyxel

The short answer

CVE-2026-7273 affects Zyxel GS1900-48HPv2 firmware and is rated high (CVSS 8.8). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-09-21: attackers are using it, so patch it first.

What it is

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.

Weakness: CWE-121.

Severity

8.8 high

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploited (CISA KEV)

Yes, since Sep 21, 2026

Federal due date Sep 24, 2026

EPSS, next 30 days

2.7%

Higher than 86% of scored CVEs

How it can be exploited

Attack vector
Adjacent network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

What CISA says to do

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…

Affected products

GS1900-48HPv2 firmware, GS1900-8 firmware, GS1900-8HP firmware, GS1900-10HP firmware, GS1900-16 firmware, GS1900-24 firmware, GS1900-24E firmware, GS1900-24EP firmware, GS1900-24HPv2 firmware, GS1900-48 firmware. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-7273 being exploited?

Yes. CISA added CVE-2026-7273 to its Known Exploited Vulnerabilities catalog on 2026-09-21, with a federal remediation due date of 2026-09-24.

How do I fix CVE-2026-7273?

CISA's required action: 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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