CVE-2026-7273

Zyxel GS1900 Series Switches Stack-Based Buffer Overflow

8.8 HIGHActively exploited (CISA KEV)Public exploitEPSS 2.50%

Published16 Jun 2026
Added to CISA KEV21 Sept 2026
Remediation due24 Sept 2026

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.

CVSS 3.1 breakdown

Attack vectorAdjacent

Attack complexityLow

Privileges requiredNone

User interactionNone

ScopeUnchanged

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Affected products

Zyxel Gs1900-10hp Firmware< 2.90\(aazi.2\)c0

Zyxel Gs1900-16 Firmware< 2.90\(aahj.2\)c0

Zyxel Gs1900-24e Firmware< 2.90\(aahk.2\)c0

Zyxel Gs1900-24ep Firmware< 2.90\(abto.2\)c0

Zyxel Gs1900-24 Firmware< 2.90\(aahl.2\)c0

Zyxel Gs1900-24hpv2 Firmware< 2.90\(abtp.2\)c0

Zyxel Gs1900-48 Firmware< 2.90\(aahn.2\)c0

Zyxel Gs1900-48hpv2 Firmware< 2.90\(abtq.2\)c0

Zyxel Gs1900-8 Firmware< 2.90\(aahh.2\)c0

Zyxel Gs1900-8hp Firmware< 2.90\(aahi.2\)c0

Remediation

Fixed in

Zyxel Gs1900-10hp Firmware≥ 2.90\(aazi.2\)c0

Zyxel Gs1900-16 Firmware≥ 2.90\(aahj.2\)c0

Zyxel Gs1900-24e Firmware≥ 2.90\(aahk.2\)c0

Zyxel Gs1900-24ep Firmware≥ 2.90\(abto.2\)c0

Zyxel Gs1900-24 Firmware≥ 2.90\(aahl.2\)c0

Zyxel Gs1900-24hpv2 Firmware≥ 2.90\(abtp.2\)c0

Zyxel Gs1900-48 Firmware≥ 2.90\(aahn.2\)c0

Zyxel Gs1900-48hpv2 Firmware≥ 2.90\(abtq.2\)c0

Zyxel Gs1900-8 Firmware≥ 2.90\(aahh.2\)c0

Zyxel Gs1900-8hp Firmware≥ 2.90\(aahi.2\)c0

Patch & vendor advisories

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

References

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273Third Party AdvisoryUS Government Resource
https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitationExploitThird Party Advisory
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026Vendor Advisory

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-7273 being actively exploited?

Yes. CVE-2026-7273 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 21 Sept 2026.

How severe is CVE-2026-7273?

CVE-2026-7273 has a CVSS 3.1 base score of 8.8, rated high. EPSS estimates a 2.50% probability of exploitation.

Which products are affected by CVE-2026-7273?

Affected products include Zyxel Gs1900-10hp Firmware, Zyxel Gs1900-16 Firmware, Zyxel Gs1900-24e Firmware, Zyxel Gs1900-24ep Firmware, Zyxel Gs1900-24 Firmware, and 5 more.

How do I fix CVE-2026-7273?

Upgrade affected software to a fixed version, for example Zyxel Gs1900-10hp Firmware 2.90\(aazi.2\)c0, Zyxel Gs1900-16 Firmware 2.90\(aahj.2\)c0, Zyxel Gs1900-24e Firmware 2.90\(aahk.2\)c0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-7273 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. Because it is on the CISA KEV list, Secuno flags any affected asset as top-priority automatically. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.