Vulnerability report

Exploited in the wild Confirmed confidence In CISA KEV

CVE-2026-7273

GS1900-48HPv2 firmware

Zyxel / GS1900-48HPv2 firmware · <= 2.90(ABTQ.1)C0

View live feed Monitor via API Watch CVE-2026-7273
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Exploited in the wild
EPSS
0.3%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-7273 is an unauthenticated vulnerability affecting Zyxel GS1900-48HPv2 firmware and 9 other products. A stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is confirmed. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Zyxel / GS1900-48HPv2 firmware <= 2.90(abtq.1)c0.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

GS1900-48HPv2 firmware

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.

Zyxel Affected
GS1900-48HPv2 firmware
<= 2.90(ABTQ.1)C0
Zyxel Affected
GS1900-8 firmware
<= 2.90(AAHH.1)C0
Zyxel Affected
GS1900-8HP firmware
<= 2.90(AAHI.1)C0
Zyxel Affected
GS1900-10HP firmware
<= 2.90(AAZI.1)C0
Zyxel Affected
GS1900-16 firmware
<= 2.90(AAHJ.1)C0
Zyxel Affected
GS1900-24 firmware
<= 2.90(AAHL.1)C0
Zyxel Affected
GS1900-24E firmware
<= 2.90(AAHK.1)C0
Zyxel Affected
GS1900-24EP firmware
<= 2.90(ABTO.1)C0
Zyxel Affected
GS1900-24HPv2 firmware
<= 2.90(ABTP.1)C0
Zyxel Affected
GS1900-48 firmware
<= 2.90(AAHN.1)C0
View vendor advisory (opens in new tab)
Published
16 Jun 2026
Exploitation Reported
21 Sep 2026
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None

Tags

edge cisa

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2026-7273
  • Vendor Advisory — zyxel.com zyxel.com · Vendor Advisory https://www.zyxel.com/global/en/support/security-advisories/zyxel-sec...

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

GreyNoise

Recorded 21 Sep 2026

A trusted third party reported exploitation.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
GreyNoise First 2026-09-21 13:20 UTC
CISA 2026-09-21 19:11 UTC
CVE 2026-09-21 19:50 UTC
The Hacker News 2026-09-22 00:00 UTC
TheHackerNews 2026-09-22 05:31 UTC
BleepingComputer 2026-09-22 08:53 UTC
Security Affairs 2026-09-22 10:20 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

No detection artifacts or sensor request patterns are available for this CVE yet.

Check back as sensor telemetry and scanner integrations are updated.

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

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

EPSS

0.3%

Weaknesses

Stack-based Buffer Overflow CWE-121

Recent mention · CyberInsider

WordPress “wp2shell” attacks stole 18,000 government records

A suspected Chinese-speaking threat actor exploited WordPress vulnerabilities to breach dozens of organizations worldwide, stealing more than 18,000 sensitive records from one Western government agency. GreyNoise researchers tracked the attacker through the company’s Global...

Read full advisory

All Mentions

Recent mention · CyberInsider

WordPress “wp2shell” attacks stole 18,000 government records

CyberInsider · 22 Sep 2026

A suspected Chinese-speaking threat actor exploited WordPress vulnerabilities to breach dozens of organizations worldwide, stealing more than 18,000 sensitive records from one Western government agency. GreyNoise researchers tracked the attacker through the company’s Global Observation Grid (GOG), a network of internet-facing sensors designed to attract scanning and exploitation attempts. GreyNoise says it has monitored malicious … The post WordPress “wp2shell” attacks stole 18,000 government records appeared first on CyberInsider.

Recent mention · Security Affairs

U.S. CISA adds Zyxel flaw to its Known Exploited Vulnerabilities catalog

Security Affairs · 22 Sep 2026

U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds Zyxel flaw to its Known Exploited Vulnerabilities catalog. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added a Zyxel GS1900 Series Switches flaw, tracked as CVE-2026-7273 (CVSS score of 8.8), to its Known Exploited Vulnerabilities (KEV) catalog. The flaw is a stack-based buffer overflow that could allow attackers […]

Recent mention · BleepingComputer

CISA orders feds to patch Zyxel flaw exploited for data theft

BleepingComputer · 22 Sep 2026

​Attackers are now actively exploiting a high-severity vulnerability in Zyxel GS1900 series switches, according to the U.S. Cybersecurity and Infrastructure Security Agency (CISA). [...]

Recent mention · The Hacker News

Zyxel and Veeam Flaws Under Active Exploitation With Command and SYSTEM Access

The Hacker News · 22 Sep 2026

Ravie LakshmananSep 22, 2026Vulnerability / Endpoint Security The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Monday added a now-patched security flaw impacting Zyxel GS1900 series switches to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence of active exploitation. The vulnerability, tracked as CVE-2026-7273 (CVSS score: 8.8), is a stack-based buffer overflow vulnerability that could result in arbitrary operating system (OS) command execution. "A stack-based buffer overflow vulnerability in the CGI program of the Zyxel GS1900 series switch firmware...

Recent mention · GreyNoise

Open Season on Kapibala: Attacker Steals Over 18,000 Government Records Through WordPress Exploitation

GreyNoise · 21 Sep 2026

GreyNoise has been tracking malicious use of an IP address since early June 2026 due to its frequent use in scans and attacks against a variety of technologies. We detail a few of the more notable intrusions we observed including the theft of more than 18,000 sensitive records from a western government.

Recent mention · Daily CyberSecurity

Zyxel Patches Stack-Based Buffer Overflow in GS1900 Switches (CVE-2026-7273)

Daily CyberSecurity · 18 Jun 2026

Zyxel has rolled out firmware patches for a serious flaw in its popular GS1900 series switches. Tracked as The post Zyxel Patches Stack-Based Buffer Overflow in GS1900 Switches (CVE-2026-7273) appeared first on Daily CyberSecurity. Related posts: Zyxel Firewalls Under Attack via Critical CVE-2023-28771 Total Takeover: Critical Zyxel Flaw (CVSS 9.8) Exposes Routers to Remote Command Injection Exploited in the Wild: Critical 9.8 CVSS RCE Hits Canon GUARDIANWALL MailSuite

Timeline

From disclosure to observed exploitation

  1. 10:20 UTC

    KEV confirmed by Security Affairs

    Exploitation attested by an external source

  2. 08:53 UTC

    KEV confirmed by BleepingComputer

    Exploitation attested by an external source

  3. 05:31 UTC

    KEV confirmed by TheHackerNews

    Exploitation attested by an external source

  4. 00:00 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  5. 19:50 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  6. 19:11 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  7. 13:20 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  8. 02:20 UTC

    CVE published

    Vulnerability disclosed publicly

  9. 06:21 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
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  • Affected versions and enrichment
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GET /api/v2/pro/kevs/CVE-2026-7273

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-7273",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.00315,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}