CVE-2026-7538
Published: 01 May 2026
Summary
CVE-2026-7538 is a critical-severity Command Injection (CWE-77) vulnerability in Totolink A8000RU (inferred from references). Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 20.4% 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 AC-3 (Access Enforcement) and SI-10 (Information Input Validation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly prevents OS command injection vulnerability by validating the manipulated 'proto' argument in the CGI handler.
Mandates timely flaw remediation through firmware updates addressing the specific command injection in Totolink A8000RU 7.1cu.643_b20200521.
Enforces approved authorizations to block unauthenticated remote access to the vulnerable /cgi-bin/cstecgi.cgi endpoint.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE-2026-7538 is a command injection vulnerability in a public-facing CGI handler on a router web interface, directly enabling exploitation of public-facing applications (T1190) and arbitrary OS command execution equivalent to abusing network device CLI (T1059.008).
NVD Description
A vulnerability was identified in Totolink A8000RU 7.1cu.643_b20200521. This issue affects the function Vulnerability of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. The manipulation of the argument proto leads to os command injection. The attack may be initiated remotely.…
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The exploit is publicly available and might be used.
Deeper analysisAI
CVE-2026-7538 is an OS command injection vulnerability (CWE-77, CWE-78) affecting the Totolink A8000RU router running firmware version 7.1cu.643_b20200521. The issue resides in the CGI Handler component, specifically the /cgi-bin/cstecgi.cgi file, where manipulation of the "proto" argument enables arbitrary command execution. It carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity due to its potential for complete system compromise.
The vulnerability is exploitable remotely by unauthenticated attackers with network access, requiring low complexity and no user interaction. Successful exploitation allows attackers to execute arbitrary operating system commands, potentially leading to full control over the device, including data theft, modification of configurations, or disruption of network services.
Advisories and details are documented on VulDB (vuln/360354 and related pages) and a GitHub repository containing a publicly available exploit at https://github.com/Litengzheng/vuldb_new2/blob/main/A8000RU/vul_329/README.md. The Totolink vendor website (https://www.totolink.net/) provides general support resources, though specific patch information for this firmware version is referenced in the linked submissions. Security practitioners should verify and apply any available firmware updates promptly.
Details
- CWE(s)