In October and November 2026, refrigeration controllers in hundreds of European supermarkets were taken over and heated to as much as 50 °C. Here is what happened – and how a Unitronics solution can close the gaps and raise the alarm if it happens anyway.
Refrigeration controllers in up to 700 supermarkets were taken over and put into defrost with the goods still in the cabinets. Temperatures rose to as much as 50 °C, and the attack set off no alarm. Losses are estimated at tens of millions of euros.
The French authority CERT-FR recommends taking the affected controllers off the internet or filtering access very tightly, installing all security fixes and changing passwords.
A supermarket chain in Estonia had a freezer set to 50 °C, and new attacks are suspected in Belgium and Sweden. Danish supermarkets have called the attacks worrying.
The controllers’ web server could be reached directly from the internet. Security researchers have found thousands of such systems.
Several systems could be accessed with a default username and a predictable password.
Some controllers had been discontinued years ago or were running firmware without the latest security fixes.
This is not a problem for one particular brand. Any networked controller – including a PLC – is vulnerable if it is openly exposed on the internet with a default password. Attacks on PLCs with default passwords have also been seen in practice.
This example is a solution outline, not a customer story. The final solution is agreed with your refrigeration technician.
In the attacks, the refrigeration controller itself was taken over – and it reported no fault. A separate controller with its own sensors sees the actual temperature and responds, even if the refrigeration controller has been compromised.
These points are based on CERT-FR’s recommendations after the attacks and apply whichever refrigeration controller you have.
Read CERT-FR’s alert (in French)We help with the router, remote access and an independent temperature monitor – together with your refrigeration technician.
This page is based on publicly available information as of 2 November 2026. It is an overview – not a security assessment of a specific system.
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