CVE-2026-112351 in SureLine
Summary
by MITRE • 10/27/2026
Sunhillo SureLine before 9.1.5 contains an OS command injection vulnerability in the networkDiag.cgi endpoint that allows an authenticated remote attacker with any web account to execute arbitrary commands as root by injecting shell metacharacters into the ipAddr or dnsAddr parameters. Attackers can bypass the incomplete character denylist from the prior CVE-2021-36380 fix using URL-encoded newline (%0a) or ampersand (%26) sequences that act as command separators after decoding in the ping, nslookup, or traceroute diagnostic modes, leading to full system compromise.
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Analysis
by VulDB Data Team • 10/27/2026
The Sunhillo SureLine network management platform prior to version 9.1.5 is susceptible to a critical OS command injection vulnerability within its web-based interface, specifically targeting the networkDiag.cgi endpoint. This flaw allows an authenticated remote attacker who possesses any valid user account on the system to execute arbitrary operating system commands with root-level privileges. The vulnerability stems from insufficient input validation and sanitization of parameters passed to diagnostic tools such as ping, nslookup, and traceroute. Specifically, the ipAddr and dnsAddr fields are processed without adequate filtering for shell metacharacters, enabling an attacker to inject malicious payloads that alter the intended command execution flow.
The technical mechanism of this exploitation relies on bypassing a previously implemented security control associated with CVE-2021-36380. The prior fix attempted to mitigate similar issues by employing a character denylist; however, this approach proved incomplete and easily circumvented through URL-encoded sequences. Attackers can utilize percent-encoded newline characters (%0a) or ampersands (%26), which are decoded by the web server before being passed to the underlying shell commands. These encoded sequences act as command separators in Unix-like environments, allowing the attacker to terminate the legitimate diagnostic request and append arbitrary system commands for execution. This technique effectively neutralizes the previous mitigation efforts that relied solely on blocking specific visible characters without accounting for encoding variations or alternative control structures.
From a classification perspective, this vulnerability aligns with CWE-78 Improper Neutralization of Special Elements used in an OS Command commonly known as OS Command Injection. The attack vector is classified under ATT&CK technique T1059 Command and Scripting Interpreter, where adversaries use system utilities to execute commands on compromised hosts. Furthermore, the ability to escalate privileges from a standard web user account to root access corresponds to CWE-269 Improper Privilege Management and represents a significant escalation of privilege scenario within the ATT&CK framework under T1078 Valid Accounts combined with T1053 Scheduled Task/Job or direct command execution depending on the specific payload used.
The operational impact of this vulnerability is severe, resulting in full system compromise. Since the injected commands are executed as root, an attacker gains complete control over the Sunhillo SureLine appliance. This level of access allows for the exfiltration of sensitive network configuration data, modification of firewall rules to facilitate lateral movement within the protected network, installation of persistent backdoors or malware, and potential disruption of critical network services. The presence of this flaw in a device often positioned at the perimeter or core of an enterprise network significantly expands the attack surface, as compromise of this single node can serve as a pivot point for broader infrastructure infiltration.
Mitigation strategies must prioritize immediate patching to version 9.1.5 or later where these input validation flaws have been addressed with robust sanitization techniques rather than simple denylists. In environments where patching is not immediately feasible, network segmentation should be enforced to restrict access to the management interface of Sunhillo devices only from trusted administrative subnets. Additionally, implementing strict web application firewall rules that detect and block URL-encoded shell metacharacters in query parameters can provide a temporary layer of defense against exploitation attempts. Continuous monitoring for anomalous outbound connections or unusual process executions originating from the network device should also be maintained to detect potential post-exploitation activities.