Someone reached into the cooling systems of several French grocery chains over the weekend and turned the temperature up. Chillers and freezers in hundreds of stores climbed toward 50C (122F), leaving shelves without fresh produce and forcing staff to bin perishable stock.
Carrefour, Coopermartive U, Intermarch and Leclerc were among the chains affected. Losses at individual shops ran into the tens of thousands of euros. The compromised hardware was refrigeration control gear built by the Danish manufacturer Danfoss, including the cold-storage units that hold food before it reaches the shop floor.
An old authentication trick that still works
Researchers at Claroty disclosed flaws in the Danfoss AK-SM 800A management interface in August 2025, and the vendor shipped firmware fixes. One of the bugs hid an authentication mechanism that accepted a code generated from the device’s own date, so anyone who reproduced the algorithm could log in as an administrator with the daily password.
Security researcher Kevin Beaumont called it trivial to automate. Danfoss said the shops it supplied were running outdated firmware.
Nobody has confirmed the older bugs were the way in. CERT-FR issued an alert covering numerous compromises of AK-SM and AK-SC controllers, none of which appeared in the original Claroty research, and told operators to cut network access, reset devices, rotate credentials and rebuild configurations.
The timing is awkward. Similar refrigeration failures hit US military commissaries in late August, and a Dutch grocery group confirmed its own network incident the same day.
