MEO, one of Portugal's largest telecommunications operators, confirmed that its network infrastructure was hit by a distributed denial-of-service (DDoS) attack that saturated its systems and disrupted customer access to websites and other services on Monday and into the early hours of Tuesday.
An official company source told Correio da Manhã that there was no intrusion and no access to MEO's data or that of its customers, and said the service had since stabilised.
A source at the operator said MEO confirmed that the incidents recorded on Monday and during the early hours of Tuesday on its international network infrastructure were caused by a distributed denial-of-service attack. The source said the incidents occurred in three separate periods: 12:45am to 2:55am, 5:30pm to 7:30pm, and 10:45pm to 1:05am, and involved high volumes of traffic that caused congestion and temporary degradation of the international network.
MEO notified Portugal's National Cybersecurity Centre of the incident. The centre described this type of attack as a malicious way of interrupting traffic to a server, service or network by overloading it.
No data breach, operator says
MEO said the attack targeted its infrastructure directly and that no intrusion occurred on its systems, and no access to or compromise of MEO or customer data took place.
The same source said MEO has monitoring, detection, control, protection and response mechanisms specifically designed for this type of incident, which allowed the company to identify the threat, mitigate the attack and restore network stability.
Accidents topped 2025 incident causes
Malicious attacks rank as the second most common cause of communications service failures in Portugal, behind accidents or natural phenomena. According to the latest report from Portugal's National Communications Authority (Anacom), covering 2025, security incidents affecting operators rose slightly from 82 to 87 cases that year.
The year was marked by a major blackout caused by a failure of the electrical grid, which accounts for the sharp rise in the total number of affected subscribers and connections, from 1.9 million to 14.6 million, the report said.
Anacom, led by Sandra Maximiano, reported that most security incidents had a simultaneous impact on more than one publicly available electronic communications service. Fixed telephone service, fixed internet access and subscription television service (TVS) were the most affected in 2025. Between 2015 and 2025, incidents attributable to causes external to the sector accounted for more than 77% of cases, according to Anacom.
What happens next
MEO said internet and mobile network services experienced faults across the country before the situation was brought under control.
