CVE-2026-36540
CVE-2026-36540 is a high-severity vulnerability with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-77.
Key facts
- Severity: High (CVSS 3.x base score 7.3)
- EPSS exploit prediction: 1% (67th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-32687
- Weakness: CWE-77
- Published:
- Last modified:
Description
Netis AC1200 Router NC21 V4.0.1.4296 is vulnerable to unauthenticated command injection via the /cgi-bin/skk_set.cgi endpoint. The password and new_pwd_confirm POST parameters are passed directly to the underlying OS shell without sanitization. An attacker can inject arbitrary shell commands by wrapping them in backticks (`) and encoding them in base64. Because the endpoint requires no authentication, any device on the LAN can achieve full Remote Code Execution on the router's operating system with a single HTTP POST request.
Frequently asked questions
- What is CVE-2026-36540?
- Netis AC1200 Router NC21 V4.0.1.4296 is vulnerable to unauthenticated command injection via the /cgi-bin/skk_set.cgi endpoint. The password and new_pwd_confirm POST parameters are passed directly to the underlying OS shell without sanitization. An attacker can inject arbitrary shell commands by wrapping them in backticks (`) and encoding them in base64. Because the endpoint requires no authentication, any device on the LAN can achieve full Remote Code Execution on the router's operating system with a single HTTP POST request.
- How severe is CVE-2026-36540?
- CVE-2026-36540 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
- Is CVE-2026-36540 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
- How do I fix CVE-2026-36540?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- Does CVE-2026-36540 have an EU (EUVD) identifier?
- Yes. CVE-2026-36540 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-32687.
- When was CVE-2026-36540 published?
- CVE-2026-36540 was published on 2026-05-27 and last updated on 2026-07-05.
References
EU advisories (EUVD)
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