CVE-2026-7273: Zyxel GS1900-48HPv2 firmware · Stack-based Buffer Overflow
Affects Zyxel GS1900-48HPv2 firmwareSource CVE Database V5
Exploited in the wild · KEV due 24 Sep 2026 · 2% EPSS : apply the vendor's fix or mitigations to Zyxel GS1900-48HPv2 firmware now.
Data as of 30 Oct 2026, 06:59 UTC
- KEV deadline
- US federal agencies must patch by this date; a sensible deadline for everyone else. Other KEV due dates
- EPSS
- 2.7% chance of exploitation in 30 days – higher than 86% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 16 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: evidence found.
Listed in CISA KEV 97 days after disclosure
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by Zyxel Corporation
, 49 days before disclosure
CVE published
on cve.org
, t = 0
In Threat Radar
record ingested
, 40 minutes after disclosure
Added to CISA KEV (opens in a new tab)
exploitation confirmed
, 97 days after disclosure
KEV remediation due
US federal deadline
, 100 days after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA KEV (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
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.
- zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026 (opens in a new tab)
- cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk (opens in a new tab)
- cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-7273 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| ZyxelGS1900-48HPv2 firmware | Affected
| Fixed in– |
| ZyxelGS1900-8 firmware | Affected
| Fixed in– |
| ZyxelGS1900-8HP firmware | Affected
| Fixed in– |
| ZyxelGS1900-10HP firmware | Affected
| Fixed in– |
| ZyxelGS1900-16 firmware | Affected
| Fixed in– |
| ZyxelGS1900-24 firmware | Affected
| Fixed in– |
Check the firmware or software version for Zyxel GS1900-48HPv2 firmware in the device's admin interface against the vendor advisory.
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.
References
- zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-stack-based-buffer-overflow-vulnerability-in-gs1900-series-switches-06-16-2026 (opens in a new tab)
- greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation (opens in a new tab)
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273 (opens in a new tab)