CVE-2026-27867 Teldat CVE debrief

Who should care

Defenders responsible for the security of Regesta Smart HD-PLC devices, particularly those with network access to the device, should assess exposure and prioritize verification of the firmware version.

Why it matters

CVE-2026-27867 is a medium-severity Cross-Site Scripting (XSS) vulnerability affecting Regesta Smart HD-PLC devices. Defenders should prioritize verifying the firmware version and ensuring it is updated to a non-vulnerable version.

• Verify firmware version and update to a non-vulnerable version if necessary
• Restrict access to the /upgrade/index.html page
• Implement input validation and sanitization for the 'cmdcookie' parameter

Technical summary

The Regesta Smart HD-PLC of Teldat is vulnerable to Cross-Site Scripting (XSS) due to improper input validation in the 'cmdcookie' parameter of the /upgrade/index.html page. An attacker with network access and the vulnerable firmware version 11.02.06.00.02 could inject a payload, potentially leading to limited impact. This issue affects Regesta Smart HD-PLC - TLDPH16D2 with firmware version 11.02.06.00.02. The CVSS score of 4.8 indicates a medium severity vulnerability. Defenders should prioritize verifying the firmware version and ensuring it is updated to a non-vulnerable version.

Defensive priority

Defenders should prioritize verifying the firmware version of Regesta Smart HD-PLC and ensuring it is updated to a non-vulnerable version.

Recommended defensive actions

• Verify the firmware version of Regesta Smart HD-PLC and update to a non-vulnerable version if necessary
• Restrict access to the /upgrade/index.html page
• Implement input validation and sanitization for the 'cmdcookie' parameter
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and NVD detail page provide information on the vulnerability, including its CVSS score and affected product. However, the corpus lacks detailed information on exploitation, impact, or remediation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.