---
id: "CVE-2026-7273"
kind: "vulnerability"
aliases: ["CVE-2026-7273"]
title: "A stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions through\u2026"
severity: "high"
cvss: 8.8
epss: null
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Zyxel GS1900 Series Switches", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "zyxel gs1900-8 firmware", "fixed": ["2.90\\(aahh.2\\)c0"], "affected": "< 2.90\\(aahh.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-8hp firmware", "fixed": ["2.90\\(aahi.2\\)c0"], "affected": "< 2.90\\(aahi.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-10hp firmware", "fixed": ["2.90\\(aazi.2\\)c0"], "affected": "< 2.90\\(aazi.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-16 firmware", "fixed": ["2.90\\(aahj.2\\)c0"], "affected": "< 2.90\\(aahj.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-24 firmware", "fixed": ["2.90\\(aahl.2\\)c0"], "affected": "< 2.90\\(aahl.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-24e firmware", "fixed": ["2.90\\(aahk.2\\)c0"], "affected": "< 2.90\\(aahk.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-24ep firmware", "fixed": ["2.90\\(abto.2\\)c0"], "affected": "< 2.90\\(abto.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-24hpv2 firmware", "fixed": ["2.90\\(abtp.2\\)c0"], "affected": "< 2.90\\(abtp.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-48 firmware", "fixed": ["2.90\\(aahn.2\\)c0"], "affected": "< 2.90\\(aahn.2\\)c0", "ecosystem": "vendor"}, {"name": "zyxel gs1900-48hpv2 firmware", "fixed": ["2.90\\(abtq.2\\)c0"], "affected": "< 2.90\\(abtq.2\\)c0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "gs1900", "infrastructure", "lan", "network-switch", "zyxel"]
not_affected_if: ["no-gs1900-deployed", "web-management-not-exposed"]
published_at: "2026-06-16T03:16:13+00:00"
first_seen_at: "2026-10-23T19:11:50+00:00"
updated_at: "2026-10-23T23:44:52+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-7273", "first_seen_at": "2026-10-23T19:11:50+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-7273", "first_seen_at": "2026-10-23T23:44:52+00:00"}]
---

# A stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions through…

Zyxel GS1900 series managed switches have a stack-based buffer overflow in their CGI web program. A LAN-based attacker with no login can send a crafted HTTP request and potentially run OS commands on the switch.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Zyxel GS1900 Series Switches affected ? fixed ?
- vendor:zyxel gs1900-8 firmware affected < 2.90\(aahh.2\)c0 fixed 2.90\(aahh.2\)c0
- vendor:zyxel gs1900-8hp firmware affected < 2.90\(aahi.2\)c0 fixed 2.90\(aahi.2\)c0
- vendor:zyxel gs1900-10hp firmware affected < 2.90\(aazi.2\)c0 fixed 2.90\(aazi.2\)c0
- vendor:zyxel gs1900-16 firmware affected < 2.90\(aahj.2\)c0 fixed 2.90\(aahj.2\)c0
- vendor:zyxel gs1900-24 firmware affected < 2.90\(aahl.2\)c0 fixed 2.90\(aahl.2\)c0
- vendor:zyxel gs1900-24e firmware affected < 2.90\(aahk.2\)c0 fixed 2.90\(aahk.2\)c0
- vendor:zyxel gs1900-24ep firmware affected < 2.90\(abto.2\)c0 fixed 2.90\(abto.2\)c0
- vendor:zyxel gs1900-24hpv2 firmware affected < 2.90\(abtp.2\)c0 fixed 2.90\(abtp.2\)c0
- vendor:zyxel gs1900-48 firmware affected < 2.90\(aahn.2\)c0 fixed 2.90\(aahn.2\)c0
- vendor:zyxel gs1900-48hpv2 firmware affected < 2.90\(abtq.2\)c0 fixed 2.90\(abtq.2\)c0

## How to check

Identify GS1900 switches on the network and check their firmware version against the vendor advisory: unknown
Check whether the switch web management interface is reachable from untrusted LAN segments: unknown
CISA lists this CVE as known exploited, so treat any unpatched GS1900 as exposed until verified.

## Fix

Apply the vendor firmware update or mitigation per Zyxel's advisory; fixed version: unknown from sources.
If no fix is available, follow CISA guidance to discontinue use of the product or isolate its management interface.

## Timeline

- 2026-10-23T19:11:50+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-7273
- 2026-10-23T23:44:52+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-7273

## From the sources

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.

CISA 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 evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_