CVE-2026-7273KEV · OVERDUECWE-121

Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability

High · published June 16, 2026

Patch now

Confirmed exploited, and the score agrees

CVSS calls it high at 8.8. It is confirmed in active exploitation. It sits in the 84.6th percentile for exploit probability.

29
days past CISA
deadline
CVSS v3.1
8.8
EPSS
3%
Percentile
84.6
In the wild
Confirmed
What it is

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.

The record
Technical detail
CVSS v3.1
8.8 · HIGH
Vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4.0
Not supplied
EPSS
0.02501 · 84.6th percentile
Weakness
CWE-121 · Stack-based Buffer Overflow
Published
2026-06-16T07:16Z
KEV added
2026-09-21 · due 2026-09-24
Affected products (10)
ProductVersionsFixed in
zyxel/gs1900-8_firmware< 2.90\(aahh.2\)c02.90\(aahh.2\)c0
zyxel/gs1900-8hp_firmware< 2.90\(aahi.2\)c02.90\(aahi.2\)c0
zyxel/gs1900-10hp_firmware< 2.90\(aazi.2\)c02.90\(aazi.2\)c0
zyxel/gs1900-16_firmware< 2.90\(aahj.2\)c02.90\(aahj.2\)c0
zyxel/gs1900-24ep_firmware< 2.90\(abto.2\)c02.90\(abto.2\)c0
zyxel/gs1900-24hpv2_firmware< 2.90\(abtp.2\)c02.90\(abtp.2\)c0
zyxel/gs1900-24_firmware< 2.90\(aahl.2\)c02.90\(aahl.2\)c0
zyxel/gs1900-24e_firmware< 2.90\(aahk.2\)c02.90\(aahk.2\)c0
zyxel/gs1900-48_firmware< 2.90\(aahn.2\)c02.90\(aahn.2\)c0
zyxel/gs1900-48hpv2_firmware< 2.90\(abtq.2\)c02.90\(abtq.2\)c0
References (3)
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 · [email protected]https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273 · 134c704f-9b21-4f2e-91b3-4a467353bcc0https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation · 134c704f-9b21-4f2e-91b3-4a467353bcc0
EPSS history
Timeline
  • 16 JUN 02:20Z
    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…
    cvelistv5