Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/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:XSummary
CVE-2026-4558 is a high-severity Command Injection (CWE-77) vulnerability in Linksys Mr9600 Firmware. Its CVSS base score is 7.4 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Command and Scripting Interpreter (T1059); ranked in the top 9% 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-2026-4558 is an OS command injection vulnerability in the smartConnectConfigure function within the SmartConnect.lua file of the Linksys MR9600 router running firmware version 2.0.6.206937. The flaw arises from improper handling of the arguments configApSsid, configApPassphrase, srpLogin, and srpPassword, allowing malicious input to execute arbitrary operating system commands. It is classified under CWE-77 (Command Injection) and CWE-78 (OS Command Injection), with a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high severity due to its potential for remote exploitation.
Attackers with low privileges (PR:L), such as authenticated users on the device, can exploit this vulnerability remotely over the network with low complexity and no user interaction required. Successful exploitation grants high-impact access to confidentiality, integrity, and availability, enabling full system compromise such as executing arbitrary commands, potentially leading to router takeover, data theft, or further network pivoting.
Advisories from VulDB (ctiid.352385, id.352385, submit.775036) and a GitHub issue (utmost3/cve/issues/1) detail the vulnerability and confirm that a public exploit is available for use. The vendor, Linksys, was notified early but has not responded or issued any patches, leaving affected devices unmitigated as per available references.
Notable context includes the published exploit, which increases the risk of real-world attacks against unpatched Linksys MR9600 routers on this firmware version. No evidence of widespread exploitation in the wild is reported in the provided data.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-14333
Vulnerability Data
A flaw has been found in Linksys MR9600 2.0.6.206937. Affected is the function smartConnectConfigure of the file SmartConnect.lua. Executing a manipulation of the argument configApSsid/configApPassphrase/srpLogin/srpPassword can lead to os command injection. The attack may be launched remotely. The exploit has…
more
been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
- 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.
Input validation directly stops construction of commands from untrusted data containing special elements.
Least privilege reduces the permissions available to any process that could be subverted by injected commands.
Least functionality restricts available OS commands and interpreters, limiting the blast radius of injection.
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.
Secure SDLC practices directly require input validation and neutralization that prevent command injection.
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.
Routine patching/maintenance can remediate known command-injection CVEs in dependencies (partial forward) but does nothing to stop developers from introducing improper neutralization in custom code (none reverse).
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.
Secure coding standards require proper escaping and parameterization of commands, directly eliminating CWE-77.
Security testing in development catches command-injection vulnerabilities before release.
Secure development life cycle mandates input validation and command construction practices that directly prevent command injection.
Application security requirements explicitly call for controls against injection flaws including command injection.
Secure architecture principles reduce the attack surface but do not prescribe the specific neutralization techniques needed.
Environment separation limits the blast radius of an exploited command injection but does not prevent the flaw itself.