CVE-2026-9404
Published: 24 May 2026
Summary
CVE-2026-9404 is a high-severity Command Injection (CWE-77) vulnerability in Totolink A8000RU (inferred from references). Its CVSS base score is 8.9 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 25.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and AC-3 (Access Enforcement).
Deeper analysis
A vulnerability identified as CVE-2026-9404 affects the Totolink A8000RU router running firmware version 7.1cu.643_b20200521. It resides in the setDdnsCfg function within the /cgi-bin/cstecgi.cgi file of the Web Management Interface, where improper handling of the provider argument enables OS command injection, corresponding to CWE-77 and CWE-78. The issue carries a CVSS 4.0 score of 8.9, reflecting network-accessible attack vectors that require no user interaction or privileges.
Remote, unauthenticated attackers can exploit the flaw by sending crafted requests to the web interface, resulting in arbitrary command execution on the device with impacts to confidentiality, integrity, and availability. A publicly available exploit has been noted in connection with this CVE.
Reference URLs include a GitHub repository containing vulnerability details and proof-of-concept material, along with entries on Vuldb and the vendor site at totolink.net; however, no specific mitigation guidance or patch information is provided in the available references. The EPSS score remains flat at 0.0125 with no observed increase from its initial value.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31607
Vulnerability details
A vulnerability was identified in Totolink A8000RU 7.1cu.643_b20200521. This affects the function setDdnsCfg of the file /cgi-bin/cstecgi.cgi of the component Web Management Interface. Such manipulation of the argument provider leads to os command injection. The attack may be launched remotely.…
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The exploit is publicly available and might be used.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote OS command injection in web management interface directly enables T1190 (Exploit Public-Facing Application) for initial access and T1059.004 (Unix Shell) for arbitrary command execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires validation and sanitization of the provider argument in setDdnsCfg to block OS command injection payloads before execution.
Enforces authentication and authorization checks on /cgi-bin/cstecgi.cgi so unauthenticated remote attackers cannot reach the vulnerable DDNS configuration function.
Boundary protection devices or WAF rules can inspect and drop crafted HTTP requests containing command-injection syntax targeting the web management interface.