VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 21 September 2026Ransomware use: unknown
Zyxel GS1900 Series Switches

CVE-2026-7273: Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 21 Sep 2026, 97 days after the CVE record was published.

How likely is exploitation in the next 30 days?
2.8%

EPSS score, percentile 86.3 of all scored records

How severe?
8.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

CISA deadline 24 Sep 2026. Apply mitigations in accordance with vendor instructions … Full text

Advisories and patches (1)

Which versions are affected?

Affected

  • <= 2.90(ABTQ.1)C0
  • <= 2.90(AAHH.1)C0
  • <= 2.90(AAHI.1)C0
  • <= 2.90(AAZI.1)C0
  • <= 2.90(AAHJ.1)C0
  • <= 2.90(AAHL.1)C0

and 4 more in the table below

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

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.

CISA due date for this action: 24 September 2026.

Advisories and patches

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Zyxel GS1900-48HPv2 firmware
StatusVersions
Affected<= 2.90(ABTQ.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-8 firmware
StatusVersions
Affected<= 2.90(AAHH.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-8HP firmware
StatusVersions
Affected<= 2.90(AAHI.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-10HP firmware
StatusVersions
Affected<= 2.90(AAZI.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-16 firmware
StatusVersions
Affected<= 2.90(AAHJ.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-24 firmware
StatusVersions
Affected<= 2.90(AAHL.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-24E firmware
StatusVersions
Affected<= 2.90(AAHK.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-24EP firmware
StatusVersions
Affected<= 2.90(ABTO.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-24HPv2 firmware
StatusVersions
Affected<= 2.90(ABTP.1)C0

Versions not listed are: unaffected.

Zyxel GS1900-48 firmware
StatusVersions
Affected<= 2.90(AAHN.1)C0

Versions not listed are: unaffected.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

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.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2026-7273 to its Known Exploited Vulnerabilities (KEV) catalog on 21 Sep 2026.
  • CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
  • The due date CISA sets for the required action is 24 Sep 2026.
  • The CVE record was published on 16 Jun 2026, 97 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 8.8 (High), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 2.8% (percentile 86.3), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

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.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

  • CWE-121: Stack-based buffer overflow

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
16 Jun 2026CVE record published
21 Sep 2026Added to CISA KEV
22 Sep 2026CVE record last updated
24 Sep 2026CISA due date for the required action

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  • CVE-2024-11667: Zyxel Multiple Firewalls Path Traversal Vulnerability (added 3 Dec 2024)
  • CVE-2017-6884: Zyxel EMG2926 Routers Command Injection Vulnerability (added 18 Sep 2023)
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