CVE-2026-5853
Published: 09 April 2026
Summary
CVE-2026-5853 is a critical-severity Command Injection (CWE-77) vulnerability in Totolink A7100RU (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 20.7% 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 SC-2 (Separation of System and User Functionality) and SI-10 (Information Input Validation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Directly validates the addrPrefixLen argument in the setIpv6LanCfg function to block OS command injection payloads.
Remediates the specific OS command injection flaw in the Totolink router's CGI handler through timely flaw remediation including firmware patching.
Separates user-supplied addrPrefixLen input from system command execution in the CGI handler to prevent injection attacks.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE enables remote exploitation of public-facing web application (T1190) on router leading to arbitrary OS command execution via network device CLI (T1059.008).
NVD Description
A security vulnerability has been detected in Totolink A7100RU 7.4cu.2313_b20191024. Affected by this vulnerability is the function setIpv6LanCfg of the file /cgi-bin/cstecgi.cgi of the component CGI Handler. Such manipulation of the argument addrPrefixLen leads to os command injection. The attack…
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may be performed from remote. The exploit has been disclosed publicly and may be used.
Deeper analysisAI
CVE-2026-5853 is an OS command injection vulnerability affecting the Totolink A7100RU router on firmware version 7.4cu.2313_b20191024. The flaw resides in the setIpv6LanCfg function within the /cgi-bin/cstecgi.cgi file of the CGI Handler component, where manipulation of the addrPrefixLen argument enables command injection.
Attackers can exploit this vulnerability remotely without authentication or user interaction, as reflected in its CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H). Successful exploitation allows arbitrary OS command execution, granting high-impact control over confidentiality, integrity, and availability of the affected device.
Advisories detail the issue on VulDB (vuln/356379 and related pages) and a GitHub repository at Litengzheng/vuldb_new, which includes the publicly disclosed exploit. The vendor site at totolink.net is referenced, but specific patch or mitigation guidance is not outlined in the disclosure.
The exploit has been publicly released and is available for use, with the vulnerability mapped to CWE-77 (Command Injection) and CWE-78 (OS Command Injection). It was published on 2026-04-09.
Details
- CWE(s)