CVE-2026-7273A stack-based buffer overflow vulnerability in the CGI program of Zyxel GS1900-48HPv2 firmware versions through 2.90(ABTQ.1)C0 could allow…
- 8.8HighCVSS base score
- 2.7%Exploitation in 30 daysEPSS · top 14% of all CVEs
- YesKnown exploitedin CISA's KEV since 21 Sept 2026
- YesPublic exploitsa reference or SSVC says so
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability.
- Added
- 21 Sept 2026
- Fix due (US federal)
- 24 Sept 2026
- Used by ransomware
- Not known
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.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 21 Sept 2026.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By Zyxel
- 49 days later
· 49 days later
Published
- 3 months later
· 3 months later
Added to CISA KEV
Known exploited in the wild
- 1 day later
· 1 day later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ZyxelCNA (assigner) | 3.1 | High8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | High8.8 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 2.7% · top 14% of all CVEs (14 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.
Affected products
Zyxel · GS1900-48HPv2 firmware
- affected <= 2.90(ABTQ.1)C0
- affected <= 2.90(AAHH.1)C0
- affected <= 2.90(AAHI.1)C0
- affected <= 2.90(AAZI.1)C0
- affected <= 2.90(AAHJ.1)C0
- affected <= 2.90(AAHL.1)C0
- affected <= 2.90(AAHK.1)C0
- affected <= 2.90(ABTO.1)C0
Zyxel · GS1900-24HPv2 firmware
- affected <= 2.90(ABTP.1)C0
- affected <= 2.90(AAHN.1)C0
References
References3
- 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 (opens in a new tab)vendor-advisory
- https://www.greynoise.io/blog/open-season-on-kapibala-attacker-steals-government-records-wordpress-exploitation (opens in a new tab)third-party-advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7273 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-37030 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-7273)Record last updated .