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Regesta Smart HD-PLC EUVDEUVD-2026-86931

| CVE-2026-27867 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-09-25 HackRTU GHSA-jj76-67xg-c9gj
4.8
CVSS 4.0 · Vendor: HackRTU
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Register/authenticate to device web UI
  2. Delivery
    Craft malicious cmdcookie payload
  3. Exploit
    Deliver crafted /upgrade/index.html request to victim
  4. Execution
    Victim browser executes injected script
  5. Impact
    Session/UI actions in victim context

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires an authenticated (registered) account on the Regesta Smart HD-PLC TLDPH16D2 web management interface running vulnerable firmware 11.02.06.00.02, plus network reachability to that interface. The attacker must inject the payload via the 'cmdcookie' parameter of the /upgrade/index.html resource, and successful exploitation depends on victim user interaction (a logged-in user must load/trigger the crafted request). Limiting factors: prior authentication (PR:L), mandatory user interaction (UI:A), the niche/industrial deployment of the device, and the specific affected firmware version all substantially narrow real-world exploitability.

Impact

This is a genuinely low-priority issue despite its network attack vector. The CVSS 4.0 base score of 4.8 (AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N) already reflects the real constraints: the attacker must be authenticated (PR:L - the description explicitly states 'registration action is required') and must lure a victim into interacting with a crafted request (UI:A), and impact is limited to low confidentiality/integrity within the browser context (VC:L/VI:L, no availability impact). There is no EPSS score, no CISA KEV listing, and no public exploit code identified at time of analysis, so all three exploitation-likelihood signals are absent or neutral. No signals conflict - the CVSS vector, the description, and the absence of exploitation evidence all point the same direction: a real-but-minor stored/reflected XSS in a niche industrial power-line-communication device's web management interface. This is a legitimate finding to patch, but not an urgent, mass-exploitable priority.

Exploit ScenarioDerived

An authenticated attacker on the device network crafts a malicious value for the 'cmdcookie' parameter of /upgrade/index.html and delivers it to another logged-in user of the Regesta Smart HD-PLC web interface. When the victim loads the crafted request, the injected payload executes JavaScript in their browser session, potentially stealing session context or performing actions in the management UI. No public proof-of-concept exploit was identified in the provided data.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 25, 2026

Cross-site scripting in Teldat's Regesta Smart HD-PLC powerline communications device (model TLDPH16D2, firmware 11.02.06.00.02) allows an attacker who already has authenticated access to the web management interface to inject a payload through the 'cmdcookie' parameter of /upgrade/index.html, which then executes in the browser of a logged-in user who triggers the crafted request. The vulnerability is confirmed only for firmware 11.02.06.00.02 and carries a low CVSS 4.0 base score of 4.8, consistent with an independent assessment of CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N that requires prior authentication (PR:L) and mandatory victim interaction (UI:R). No public exploit code and no confirmed active exploitation were identified at time of analysis, and the niche industrial deployment of these PLC devices further narrows real-world exploitability.

RemediationAI

Patch available per vendor advisory: Teldat states a fix is available from the vendor, though the input data does not specify an exact fixed firmware version, so administrators should obtain the current firmware release and upgrade instructions through the Teldat global support portal (https://support.teldat.com/portal/supportcontent?page=cgs-customer-global-support&none=true&language=en-US) and confirm applicability against the HackRTU advisories CNA-HRTU-0004 and CNA-CVE-2026-27867 (https://www.hackrtu.com/blog/CNA-HRTU-0004/, https://www.hackrtu.com/blog/CNA-CVE-2026-27867/). Where immediate upgrade is not possible, compensating controls are: restrict network reachability to the device's web management interface so that only a trusted management VLAN or jump host can reach TCP 80/443 (side effect: remote administration and monitoring must be rerouted through that path), disable remote/WAN-side management if the device supports it (side effect: no out-of-band administration during outages), and enforce a strict policy that operators never browse other sites or open untrusted links while logged into the device, combined with short session timeouts and logout after configuration (side effect: reduced convenience and more frequent re-authentication). Because exploitation requires an authenticated account plus victim interaction, the highest-value hardening is strong, unique administrator credentials, removal of unused accounts, and alerting on unexpected POST requests to /upgrade/index.html; note that these measures reduce exposure but do not fix the underlying input-handling flaw, so firmware upgrade remains the only complete remediation.

Affected VersionsENISA

Regesta Smart HD-PLC - TLDPH16D2 11.02.06.00.02

Affected Packages

euvd regesta_smart_hd_plc_tldph16d2 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The root cause is CWE-79 (Improper Neutralization of Input During Web Page Generation, i.e. cross-site scripting) in the embedded web management interface of the Teldat Regesta Smart HD-PLC. HD-PLC (High Definition Power Line Communication) devices bridge Ethernet/IP traffic over existing electrical wiring and are typically deployed in industrial, utility and building-management networks; the TLDPH16D2 is such a unit and exposes an administrative HTTP interface where the affected resource /upgrade/index.html processes a parameter named 'cmdcookie' without adequate output encoding or sanitization. The CPE string cpe:2.3:a:teldat:regesta_smart_hd-plc_-_tldph16d2:*:*:*:*:*:*:*:* identifies the affected product family, which the advisory ties specifically to firmware 11.02.06.00.02. Because the injected script executes in the security context of the device's web origin, the CVSS scope is marked Changed (S:C) with low confidentiality and integrity impact and no availability impact; exploitation presupposes that the attacker already holds a registered/authenticated session on the interface and that a logged-in user subsequently loads or triggers the crafted request, which is why the practical risk is assessed as low.

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Severity by source

Vendor (HackRTU) PRIMARY 4.8 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
vuln.today AI 5.4 MEDIUM

Authenticated web-interface user (PR:L) plus required victim interaction (UI:R) for a reflected XSS executing in the browser (S:C, C:L/I:L, no availability impact).

3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (HackRTU).

CVSS VectorVendor: HackRTU

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
Low
User Interaction
Active
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
Low
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

DescriptionCVE.org

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

Threat Intelligence Overview

EPSS Score
0.4%
Top 72% exploitable
Prevalence
Low
niche Teldat industrial power-line-communication device, limited deployment
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

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