Responsible Disclosure Disclaimer: Syndis delayed the publication of these results until all identified parties had been notified of the situation and given a chance to remediate.

What Companies in the Food and Refrigeration Industry Need to Know and Do Immediately

In March 2025, serious security flaws were discovered in Danfoss AK-SM 800A refrigeration controllers, and security engineers at Claroty (Team82) published details about them in August 2026. These controllers are widely used in supermarkets, cold storage facilities, warehouses, and other commercial buildings to manage refrigeration systems and monitor temperature and humidity levels. The vulnerabilities allow hackers to bypass authentication, execute arbitrary commands on the devices, and cause operational disruptions and potential damage. Recent large-scale attacks have targeted supermarkets in France, and though a security patch exists, Syndis has confirmed that vulnerable devices are still widely in use and accessible on the internet.

What is the risk?

The Danfoss AK-SM 800A control unit serves as a central hub for multiple refrigeration units at a given location. If an attacker gains control of the unit through its web interface, they can:

• Alter temperature limits and turn off cooling, leading to the spoilage of food or other sensitive assets.
• Change alarm thresholds or disable notifications so that operators are unaware of failures.
• Cause production or system outages (Denial of Service).
• Create risks of inventory loss, regulatory fines, or even health hazards from spoiled refrigerated and frozen goods.

How Can Hackers Reach the Devices?

Many operators connect these control units to the internet to facilitate remote maintenance and monitoring. Syndis scans have shown that a significant number of these devices are publicly accessible on the internet.

What Needs to Be Done Immediately?

1. Make devices inaccessible from the internet: If the control unit is accessible on the internet without a VPN connection, block that access immediately.
2. Update firmware: Danfoss has released security update R4.3.1 which fixes these vulnerabilities.

Next Steps and Assistance

If you are in doubt about whether refrigeration controllers or other industrial control systems (OT/ICS) at your company are at risk, contact our security experts at Syndis for assistance with risk assessment and vulnerability scanning.