A cyberattack has forced supermarket refrigeration units across France, Belgium and the Netherlands into a continuous defrost cycle at 50 degrees Celsius, with early losses already approaching 300,000 euros, La Dépêche reports.

The attack targets Danfoss-made refrigeration controls deployed by major French retailers Intermarché, Leclerc and Coopérative U. Instead of the normal two-hour daily defrost window, hackers reconfigured the automatic defrosting function to run continuously at 50 degrees Celsius. Sources quoted by the French outlet described "a wave of heat" escaping from affected fridges and freezers.

Coopérative U president Dominique Schelcher confirmed the incident on Monday morning, saying: "A cyberattack has been affecting the refrigeration production facilities of several stores in our network since last night." Schelcher said teams had mobilized to fix the problem and promised an investigation into what he called an "extremely serious" incident.

How large are the losses?

Early estimates put damage at nearly 300,000 euros, but the total could reach several million euros nationwide, according to the report. Perishable inventory in continuously defrosting cabinets rarely survives such conditions, and replacement stock adds to the bill.

The financial figure covers the French retailers named so far. It remains unclear how many stores are affected and whether additional chains will disclose incidents in the coming days.

Is a second, related attack underway?

Possibly. Dutch broadcaster NOS reports that several supermarket chains in the Netherlands suffered a malfunction from a separate cybersecurity incident on Sunday afternoon. Albert Heijn, Etos and Gall & Gall took their websites down, disrupting deliveries.

Electronic shelf labels have also been compromised, breaking in-store pricing systems. Images posted online show stores in Amsterdam warning customers about price problems. Loyalty programs have been suspended as well.

"We have immediately taken measures to protect our IT environment. Part of this involves the preventive temporary shutdown of a number of systems," Albert Heijn said in a statement.

Belgium's Delhaize chain, which belongs to Albert Heijn, has also reported disruption. At this stage, nobody has established whether the two attacks are related, or how widespread either of them is.

Why does refrigeration control matter as an attack surface?

The incident highlights the exposure of building-management and industrial control equipment — in this case Danfoss refrigeration controllers — when it sits on networks reachable from compromised IT systems. The attackers did not need to physically damage hardware; they changed configuration values, flipping a routine two-hour defrost cycle into a permanent one at 50 degrees Celsius.

The collateral damage spread quickly beyond spoiled food. Deliveries stopped, shelf labels displayed unreliable prices, and loyalty schemes went offline — the operational spine of a modern supermarket, hit from a single control layer.

Schelcher's promise of an investigation, and Albert Heijn's preventive shutdowns, suggest both companies expect the disruption to persist while systems are verified. With losses potentially running into millions of euros and the attackers' access route still unidentified, retailers across Europe will be reviewing who can reach their refrigeration controllers — and at what temperature those credentials are stored.