A large-scale cyberattack targeting connected refrigeration systems has disrupted hundreds of supermarkets across France. The attack caused refrigerators and freezers to reach 50°C (122°F), spoiling food and triggering fires. Authorities are investigating whether the incident has affected businesses in other European countries.

The Paris prosecutor’s office confirmed that a “large-scale" cyberattack had hit connected refrigeration systems at several major food retailers. French Prime Minister Sebastien Lecornu directed the National Cybersecurity Agency (ANSSI) to investigate. Authorities are also working with European counterparts to assess the attack’s wider impact.

Felix Aime, a senior cyber threat intelligence analyst at Sekoia Threat Detection and Research, said Spain, Portugal, Poland, Germany and Belgium had also been affected.

Carrefour reported disruptions at 80 supermarkets, while around 5% of Monoprix’s nearly 490 French stores were affected. Les Mousquetaires, the parent company of Intermarche, said refrigeration systems at around 150 stores were hit. Temperatures reached 50°IntermarchéC for six hours overnight. Cooperative U CEO Dominique Schelcher also confirmed that the group had been targeted.

Les Mousquetaires said staff discarded all affected food to prevent health risks. Intermarché CEO Thierry Cotillard told French broadcaster BFM TV that the “unprecedented" attack could cause nationwide losses worth tens of millions of euros in a single day. E.Leclerc and Auchan did not immediately respond to requests for comment.

The attack forced supermarkets to dispose of refrigerated and frozen products that were no longer safe to consume. Some stores also closed affected sections while restoring normal operations.

Paris resident Geert de Clercq saw staff at an Intermarché store in central Paris throw carts of defrosted frozen food into a large waste container. Melted ice cream spilt from broken tubs onto the street.

The French retail association Federation du Commerce et de la Distribution (FCD) urged refrigeration equipment supplier Danfoss to provide “full transparency" about the incident. It said retailers were protecting consumers and restoring operations, with some affected stores already back in business.

Authorities have yet to establish the total industry-wide losses. Christel Delberghe, director general of European retail association EuroCommerce, said the incident highlighted the importance of resilience across the entire supply chain.

Supermarkets often use central control panels to manage refrigeration temperatures across their stores. Maintenance companies can access these systems remotely through the internet to monitor and adjust equipment.

The company said the affected units were running outdated firmware. It added that it had long advised customers to update supported systems and replace legacy equipment with current-generation solutions.

The French attack resembles disruptions at around a dozen US military commissaries in late August, where refrigeration problems reportedly caused food losses. Cybersecurity experts have also reported possible impacts on businesses across Spain, Portugal, Poland, Germany and Belgium.