Huawei zero-day attack behind last year’s crash of Luxembourg's entire telecoms network

A previously unknown vulnerability in Huawei enterprise router software was exploited on July 23, 2025, triggering specially crafted network traffic that forced routers into continuous reboot loops and caused a nationwide outage of landline, 4G and 5G services in Luxembourg for more than three hours; investigators characterized it as a zero-day denial-of-service condition, no CVE or public advisory has been issued, and the patch/extent of exposure to other operators remains unclear.