CVE-2026-27867 in Regesta Smart HD-PLC
Summary
by MITRE • 09/25/2026
An attacker with access via network to the Regesta Smart HD-PLC of the provider Teldat (in this case, registration action is required) who has the vulnerable firmware version could inject a specific payload via the parameter "cmdcookie" withing the /upgrade/index.html resulting in to a Cross-Site Scripting (XSS). This issue affects Regesta Smart HD-PLC - TLDPH16D2: 11.02.06.00.02
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Analysis
by VulDB Data Team • 09/25/2026
The vulnerability identified involves a Cross-Site Scripting flaw within the web management interface of the Teldat Regesta Smart HD-PLC, specifically affecting firmware version 11.02.06.00.02 and model TLDPH16D2. This security issue stems from insufficient input validation on the server side when processing requests directed at the /upgrade/index.html endpoint. The specific parameter exploited is cmdcookie, which serves as a mechanism for maintaining session state or tracking upgrade progress during firmware updates. Because this parameter accepts user-supplied data without adequate sanitization, an attacker can inject malicious JavaScript code directly into the HTTP response returned by the device's web server.
From a technical perspective, the flaw represents a classic reflected Cross-Site Scripting vulnerability where untrusted input is echoed back to the client in an unsafe manner. When a victim user interacts with the compromised endpoint or views a page containing the injected payload, their browser executes the malicious script within the context of the device's administrative interface. This execution environment grants the attacker significant privileges because they are operating as if they were the authenticated administrator. The requirement for network access and registration action implies that the attacker must first authenticate to the system, which limits the attack vector to internal networks or scenarios where initial authentication credentials have been compromised through phishing or other means.
The operational impact of this vulnerability is severe due to the critical nature of Industrial Control System management interfaces. Successful exploitation allows an authenticated attacker to perform actions on behalf of the administrator without their knowledge or consent. This can include modifying network configurations, disabling security features, installing backdoors, or exfiltrating sensitive configuration data and credentials stored within the device's memory. In an industrial setting such as a power distribution grid managed by HD-PLC technology, such unauthorized changes could lead to service disruptions, operational instability, or serve as an initial foothold for more sophisticated attacks targeting broader network infrastructure.
This vulnerability aligns with CWE-79, which describes Improper Neutralization of Input During Web Page Generation known as Cross-site Scripting. The attack technique is categorized under MITRE ATT&CK ID T1059, specifically Command and Scripting Interpretation via browser-based execution, or potentially T1136 if the goal involves creating accounts for persistent access. It also relates to CWE-284 regarding Improper Access Control, as the vulnerability allows actions that should be restricted based on user roles but are instead executed due to code injection bypassing intended logic flows.
Mitigation strategies primarily involve applying the vendor-provided firmware update that addresses this input validation deficiency immediately upon availability. Until patches are applied, administrators should restrict access to the device's web interface using strict firewall rules, ensuring it is only accessible from trusted management networks and not exposed to untrusted zones like the internet or general corporate LANs. Additionally, implementing a Web Application Firewall with specific rule sets capable of detecting and blocking XSS payloads in HTTP parameters can provide an additional layer of defense. Regular auditing of administrative logs for unusual activity related to firmware upgrades or configuration changes is also recommended to detect potential exploitation attempts early.