CVE-2026-9387
Published: 24 May 2026
Summary
CVE-2026-9387 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-17 (Remote Access).
Deeper analysis
A security flaw has been discovered in Totolink A8000RU version 7.1cu.643_b20200521. The affected element is the function setUpgradeFW of the file /cgi-bin/cstecgi.cgi of the component Web Management Interface. Performing a manipulation of the argument resetFlags results in os command injection. It is possible to initiate the attack remotely. The exploit has been released to the public and may be used for attacks.
Remote unauthenticated attackers can target the web management interface over the network to inject and execute arbitrary operating system commands by supplying crafted values to the resetFlags parameter. Successful exploitation grants full control over the device, enabling impacts to confidentiality, integrity, and availability consistent with the reported CVSS 8.9 rating and the associated CWE-77 and CWE-78 classifications.
Public references include a detailed proof-of-concept on GitHub along with entries in VulDB, but no vendor advisory or patch information is provided in the available sources. The EPSS score remains flat at 0.0125 with no observed increase after disclosure.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31543
Vulnerability details
A security flaw has been discovered in Totolink A8000RU 7.1cu.643_b20200521. The affected element is the function setUpgradeFW of the file /cgi-bin/cstecgi.cgi of the component Web Management Interface. Performing a manipulation of the argument resetFlags results in os command injection. It…
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is possible to initiate the attack remotely. The exploit has been released to the public and may be used for attacks.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Remote OS command injection in web management interface (setUpgradeFW/resetFlags) directly enables T1190 exploitation of public-facing app and T1059.004 Unix shell command execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly blocks OS command injection by requiring validation and sanitization of the resetFlags argument before it reaches setUpgradeFW.
Restricts remote network access to the web management interface (/cgi-bin/cstecgi.cgi), reducing the attack surface for unauthenticated exploitation.
Enforces boundary protection to isolate or filter traffic to the management interface, preventing remote unauthenticated command injection attempts from reaching the device.