Huawei Zero-Day Flaw Causes Telecom Outage in Luxembourg

On July 23, 2025, a nationwide telecom outage in Luxembourg was attributed to a zero-day vulnerability in Huawei enterprise routers. The flaw allowed specially crafted network traffic to exploit undocumented behavior, resulting in continuous reboot loops of the routers. This incident disrupted landline, 4G, 5G, and emergency services for over three hours. Paul Rausch from POST Luxembourg confirmed that the attack was not a typical DDoS and did not target POST specifically. Huawei acknowledged the attack as unprecedented and stated that no immediate fix was available. Investigators found no similar attacks occurred afterward, raising concerns about the lack of public disclosure and potential exposure of similar systems. No CVE or advisory has been issued regarding this vulnerability.

Key Points: • A zero-day vulnerability in Huawei routers caused a nationwide telecom outage in Luxembourg. • The outage lasted over three hours, affecting all communication services including emergency lines. • Huawei has not provided a patch or public disclosure for the undocumented flaw.