CVE-2026-5020
Command Injection in Totolink A3600R Firmware 4.1.2cu.5182_b20201102
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-5020 is a medium-severity Injection (CWE-74) vulnerability in Totolink A3600R Firmware. Its CVSS base score is 5.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Dynamic Linker Hijacking (T1574.006); ranked in the top 16% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-5020 is a command injection vulnerability affecting the Totolink A3600R router on firmware version 4.1.2cu.5182_B20201102. The flaw resides in the setNoticeCfg function of the /cgi-bin/cstecgi.cgi file within the Parameter Handler component, where manipulation of the NoticeUrl argument enables command injection. Published on 2026-03-29, it carries a CVSS v3.1 base score of 6.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L) and maps to CWEs-74 and CWE-77.
The vulnerability is exploitable remotely over the network with low attack complexity, requiring low privileges such as an authenticated user account and no user interaction. Attackers can inject commands via the NoticeUrl parameter, potentially leading to limited impacts on confidentiality, integrity, and availability, such as unauthorized data access, modification, or service disruption on the affected device.
Advisories and further details are documented in references including VulDB entries (vuldb.com/vuln/353905 and related pages) and a public exploit proof-of-concept on a Notion site. The vendor site at www.totolink.net provides additional context, though specific patch information is not detailed in the primary disclosure.
The exploit is public and available for use, increasing the risk of real-world exploitation against unpatched Totolink A3600R devices.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-16961
Vulnerability Data
A vulnerability was detected in Totolink A3600R 4.1.2cu.5182_B20201102. Affected by this issue is the function setNoticeCfg of the file /cgi-bin/cstecgi.cgi of the component Parameter Handler. The manipulation of the argument NoticeUrl results in command injection. The attack may be launched…
more
remotely. The exploit is now public and may be used.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover command-construction flaws before deployment.
SI-10 directly requires validation of information inputs to reject malformed or special-element content before it reaches downstream parsers.
Secure engineering principles include proper neutralization and safe command construction practices.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Runtime monitoring of software and data can detect anomalous command execution resulting from injection.
Identifying recorded vulnerabilities enables remediation of command-injection flaws before exploitation.
Secure SDLC practices directly require input validation and output encoding that prevent injection flaws.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Logging supports detection of injection attempts but does not prevent the weakness.
Monitoring activities can identify active injection attacks after they occur.
Secure development life cycle mandates input validation and output encoding that directly prevent injection flaws.
Application security requirements explicitly call for controls against injection attacks in software design.
Secure architecture principles reduce injection surfaces but do not prescribe specific neutralization techniques.
Secure coding standards require proper neutralization of special elements, directly addressing CWE-74.