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Known Exploited Vulnerability
8.8
HIGH CVSS 3.1
CVE-2026-7273
Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability - [Actively Exploited]
Overview
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.

Details
INFO

Published Date :

June 16, 2026, 3:16 a.m.

Last Modified :

Sept. 22, 2026, 12:10 p.m.

Remotely Exploit :

No

Source :

[email protected]
CISA Notification
CISA KEV (Known Exploited Vulnerabilities)

For the benefit of the cybersecurity community and network defenders—and to help every organization better manage vulnerabilities and keep pace with threat activity—CISA maintains the authoritative source of vulnerabilities that have been exploited in the wild.

Description :

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.

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.

Known Ransomware Campaign Use:

Unknown

Notes :

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 ; ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-7273

Impact
Affected Products

The following products are affected by CVE-2026-7273 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Zyxel gs1900-8_firmware
2 Zyxel gs1900-24_firmware
3 Zyxel gs1900-8hp_firmware
4 Zyxel gs1900-10hp_firmware
5 Zyxel gs1900-16_firmware
6 Zyxel gs1900-24e_firmware
7 Zyxel gs1900-48_firmware
8 Zyxel gs1900-24ep_firmware
9 Zyxel gs1900-24hpv2_firmware
10 Zyxel gs1900-48hpv2_firmware
11 Zyxel gs1900-48hpv2
12 Zyxel gs1900-48
13 Zyxel gs1900-24hpv2
14 Zyxel gs1900-24ep
15 Zyxel gs1900-24e
16 Zyxel gs1900-24
17 Zyxel gs1900-16
18 Zyxel gs1900-10hp
19 Zyxel gs1900-8hp
20 Zyxel gs1900-8
: Total Affected Vendor : 1 | Products : 20
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 134c704f-9b21-4f2e-91b3-4a467353bcc0
CVSS 3.1 HIGH 96e50032-ad0d-4058-a115-4d2c13821f9f
CVSS 3.1 HIGH [email protected]
Solution
Update Zyxel firmware to patch stack overflow and prevent command execution.
  • Update the device firmware.
  • Apply security patches from the vendor.
  • Restrict network access to the device.
  • Monitor for suspicious HTTP requests.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-7273.

URL Resource
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 Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273 Third Party Advisory US Government Resource
https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation Exploit Third Party Advisory
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-7273 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-7273 weaknesses.

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-7273 vulnerability anywhere in the article.

  • TheCyberThrone
CISA adds Five Vulnerabilities to Exploitable Catalog

CISA’s Known Exploited Vulnerabilities (KEV) Catalog continues to highlight a familiar pattern: vulnerabilities affecting network infrastructure,  security appliances and management platforms are beco ... Read more

Published Date: Sep 23, 2026 (2 weeks, 4 days ago)
  • security.nl
CISA meldt actief misbruik van stackoverflow in Zyxel switch

Het Cybersecurity and Infrastructure Security Agency (CISA) waarschuwt voor actief misbruik van een kritieke kwetsbaarheid in Zyxel switches. De kwetsbaarheid (CVE-2026-7273), een klassieke stackoverf ... Read more

Published Date: Sep 22, 2026 (2 weeks, 4 days ago)
  • The Hacker News
Zyxel and Veeam Flaws Under Active Exploitation With Command and SYSTEM Access

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 ... Read more

Published Date: Sep 22, 2026 (2 weeks, 4 days ago)

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-7273 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • Initial Analysis by [email protected]

    Sep. 22, 2026

    Action Type Old Value New Value
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-8_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aahh.2)c0 OR cpe:2.3:h:zyxel:gs1900-8:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-8hp_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aahi.2)c0 OR cpe:2.3:h:zyxel:gs1900-8hp:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-10hp_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aazi.2)c0 OR cpe:2.3:h:zyxel:gs1900-10hp:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-16_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aahj.2)c0 OR cpe:2.3:h:zyxel:gs1900-16:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-24_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aahl.2)c0 OR cpe:2.3:h:zyxel:gs1900-24:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-24e_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aahk.2)c0 OR cpe:2.3:h:zyxel:gs1900-24e:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-24ep_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(abto.2)c0 OR cpe:2.3:h:zyxel:gs1900-24ep:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-24hpv2_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(abtp.2)c0 OR cpe:2.3:h:zyxel:gs1900-24hpv2:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-48_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(aahn.2)c0 OR cpe:2.3:h:zyxel:gs1900-48:-:*:*:*:*:*:*:*
    Added CPE Configuration AND OR *cpe:2.3:o:zyxel:gs1900-48hpv2_firmware:*:*:*:*:*:*:*:* versions up to (excluding) 2.90(abtq.2)c0 OR cpe:2.3:h:zyxel:gs1900-48hpv2:-:*:*:*:*:*:*:*
    Added Reference Type Zyxel Corporation: 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 Types: Vendor Advisory
    Added Reference Type CISA-ADP: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273 Types: Third Party Advisory, US Government Resource
    Added Reference Type CISA-ADP: https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation Types: Exploit, Third Party Advisory
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 22, 2026

    Action Type Old Value New Value
    Changed SSVC {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-21T19:40:05.862596Z'} {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-17T00:00:00+00:00'}
  • CVE CISA KEV Update by 9119a7d8-5eab-497f-8521-727c672e3725

    Sep. 21, 2026

    Action Type Old Value New Value
    Added Date Added 2026-09-21
    Added Due Date 2026-09-21
    Added Required Action 2026-09-21
    Added Vulnerability Name 2026-09-21
  • CVE Modified by [email protected]

    Sep. 21, 2026

    Action Type Old Value New Value
    Added Reference 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
    Removed Reference 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
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Sep. 21, 2026

    Action Type Old Value New Value
    Added Reference https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273
    Added Reference https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation
    Changed SSVC {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-17T00:00:00+00:00'} {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'active'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-21T19:40:05.862596Z'}
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jun. 18, 2026

    Action Type Old Value New Value
    Changed SSVC {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-16T12:38:10.254142Z'} {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-17T00:00:00+00:00'}
  • CVE Modified by [email protected]

    Jun. 17, 2026

    Action Type Old Value New Value
    Added Affected [{'vendor': 'Zyxel', 'product': 'GS1900-48HPv2 firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(ABTQ.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-8 firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAHH.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-8HP firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAHI.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-10HP firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAZI.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-16 firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAHJ.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-24 firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAHL.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-24E firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAHK.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-24EP firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(ABTO.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-24HPv2 firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(ABTP.1)C0'}], 'defaultStatus': 'unaffected'}, {'vendor': 'Zyxel', 'product': 'GS1900-48 firmware', 'versions': [{'status': 'affected', 'version': '<= 2.90(AAHN.1)C0'}], 'defaultStatus': 'unaffected'}]
  • CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0

    Jun. 17, 2026

    Action Type Old Value New Value
    Added SSVC {'id': 'CVE-2026-7273', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-16T12:38:10.254142Z'}
  • New CVE Received by [email protected]

    Jun. 16, 2026

    Action Type Old Value New Value
    Added 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.
    Added CVSS V3.1 AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    Added CWE CWE-121
    Added Reference 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
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 8.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact