Miljödata attack disables HR systems across Swedish municipalities and regions

An attack against Swedish system provider Miljödata on 23 August 2025 encrypted data and made hosted HR, rehabilitation and work-environment systems unavailable to numerous customer organizations. Sweden's privacy regulator reported at least 164 municipalities and four regions affected, while independent reporting described key municipal systems going dark. Later regulatory reporting confirmed data exfiltration and publication; established reporting characterized the incident as ransomware.