Zyxel GS1900 Series Switches Stack-Based Buffer Overflow Vulnerability
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…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 2 / 5
- KEV catalog (CISA)21 Sept 2026
- Exploited in EUVD (ENISA)21 Sept 2026
- Used by ransomwareno
- EPSS above 10 %2.8%
- No account, over the networkno
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: 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.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
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.
Affected products
- ≤ 2.90(ABTO.1)C0
- ≤ 2.90(ABTP.1)C0
- ≤ 2.90(AAHJ.1)C0
- ≤ 2.90(AAHI.1)C0
- ≤ 2.90(ABTQ.1)C0
- ≤ 2.90(AAHK.1)C0
- ≤ 2.90(AAHL.1)C0
- ≤ 2.90(AAHN.1)C0
- ≤ 2.90(AAHH.1)C0
- ≤ 2.90(AAZI.1)C0
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
References
Other exploited vulnerabilities from the same vendor
- CVE-2024-40891Zyxel DSL CPE OS Command Injection Vulnerability6.0 · Background exploitation
- CVE-2024-40890Zyxel DSL CPE OS Command Injection Vulnerability5.9 · Background exploitation
- CVE-2024-11667Zyxel Multiple Firewalls Path Traversal Vulnerability5.5 · Background exploitation
- CVE-2017-6884Zyxel EMG2926 Routers Command Injection Vulnerability6.9 · Background exploitation
- CVE-2017-18368Zyxel P660HN-T1A Routers Command Injection Vulnerability9.2 · Background exploitation
- CVE-2023-27992Zyxel Multiple NAS Devices Command Injection Vulnerability8.8 · Background exploitation