CVE-2026-7273
High8.8CISA KEV — exploited in the wildZyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerabilityname from CISA KEV
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.
- CVSS
- 8.8v3.1
- EPSS (exploit probability)
- 2.8%86th pct
- CISA KEV
- Listed
EPSS trendFIRST daily scores, last 90 days
Daily values
| Score date | EPSS | Percentile |
|---|---|---|
| 2026-11-04 | 2.8% | 86.4% |
| 2026-11-03 | 2.8% | 86.4% |
| 2026-11-02 | 2.8% | 86.4% |
| 2026-11-01 | 2.8% | 86.4% |
| 2026-10-31 | 2.8% | 86.4% |
| 2026-10-30 | 2.8% | 86.4% |
| 2026-10-29 | 2.8% | 86.3% |
| 2026-10-28 | 2.8% | 86.3% |
| 2026-10-27 | 2.8% | 86.3% |
| 2026-10-26 | 2.8% | 86.3% |
| 2026-10-25 | 2.8% | 86.3% |
| 2026-10-24 | 2.5% | 84.6% |
| 2026-10-23 | 2.5% | 84.6% |
| 2026-10-22 | 2.5% | 84.6% |
| 2026-10-21 | 2.5% | 84.6% |
| 2026-10-20 | 2.5% | 84.5% |
| 2026-10-19 | 2.5% | 84.5% |
| 2026-10-18 | 2.5% | 84.5% |
| 2026-10-17 | 2.5% | 84.5% |
| 2026-10-16 | 2.5% | 84.4% |
| 2026-10-15 | 2.5% | 84.4% |
| 2026-10-14 | 2.5% | 84.4% |
| 2026-10-13 | 2.5% | 84.3% |
| 2026-10-12 | 2.5% | 84.3% |
| 2026-10-11 | 2.5% | 84.3% |
| 2026-10-10 | 2.5% | 84.3% |
| 2026-10-09 | 2.5% | 84.2% |
| 2026-10-08 | 2.5% | 84.2% |
| 2026-10-07 | 2.5% | 84.2% |
| 2026-10-06 | 2.5% | 84.2% |
| 2026-10-05 | 2.5% | 84.2% |
CISA KEV entrycatalogue 2026.11.04
- Date added
- 2026-09-21
- Federal due date
- 2026-09-24
- Known ransomware use
- Unknown
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.
Verbatim from the CISA KEV catalogue (CISA KEV, fetched 2026-11-05 13:20 UTC). The due date applies to US federal agencies under BOD 22-01.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Learn
Why it happened and what stops it
The weakness (CWE)
How attackers use it (ATT&CK)
Typical for this kind of weakness across CISA KEV exploits (CTID), not specific to this CVE.
How it's exploited
What the attacker gets
Controls that mitigate it (NIST SP 800-53)
- CM-6Configuration SettingsConfiguration Management · mitigates 8 of these techniques
- SI-3Malicious Code ProtectionSystem and Information Integrity · mitigates 8 of these techniques
- SI-4System MonitoringSystem and Information Integrity · mitigates 8 of these techniques
- CA-7Continuous MonitoringSecurity Assessment and Authorization · mitigates 7 of these techniques
- CM-7Least FunctionalityConfiguration Management · mitigates 7 of these techniques
- AC-4Information Flow EnforcementAccess Control · mitigates 6 of these techniques
Affected products
- zyxel gs1900-8 firmware
- zyxel gs1900-8
- zyxel gs1900-8hp firmware
- zyxel gs1900-8hp
- zyxel gs1900-10hp firmware
- zyxel gs1900-10hp
- zyxel gs1900-16 firmware
- zyxel gs1900-16
- zyxel gs1900-24 firmware
- zyxel gs1900-24
- zyxel gs1900-24e firmware
- zyxel gs1900-24e
- zyxel gs1900-24ep firmware
- zyxel gs1900-24ep
- zyxel gs1900-24hpv2 firmware
- zyxel gs1900-24hpv2
- zyxel gs1900-48 firmware
- zyxel gs1900-48
- zyxel gs1900-48hpv2 firmware
- zyxel gs1900-48hpv2
Coverage1 article
References
- 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
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273
- https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation