On 24 September 2026, Belnet identified a security and privacy incident within its IT infrastructure. The incident was caused by the exploitation of a zero-day vulnerability affecting technology provided by an external supplier.
What happened?
On 24 September 2026, Belnet identified a security and privacy incident within its IT infrastructure. The incident was caused by the exploitation of a zero-day vulnerability affecting technology provided by an external supplier.
Upon detecting the incident, Belnet immediately took measures to stop the incident, address the vulnerability and contain the data breach. The vulnerability was remediated on Friday, 25 September at 08:10.
Belnet has engaged the Centre for Cybersecurity Belgium (CCB) for additional expertise in incident response and forensic investigation. The competent authorities have also been informed in accordance with our regulatory obligations. Belnet has immediately implemented additional security measures to improve the security of the service and continues to monitor the situation closely. We are conducting a thorough investigation to determine the precise nature and scope of the incident and to identify any other parties that may have been affected.
What data was affected?
Based on our investigation to date, we have established that the incident affected emails processed through the impacted infrastructure between 22 July 2026 and the morning of Friday, 25 September 2026.
This includes all incoming emails sent to domains owned by Belnet/BNIX email addresses including the sender details, content of those emails and any attachments.
During the affected period, emails were copied by the attackers and transferred to external infrastructure. Belnet has directly informed its customers about the incident and the measures they should take.
Ongoing investigation
Belnet continues to monitor the situation closely and is pursuing its investigation. We will continue to provide relevant updates as our investigation progresses.
At this stage, no further information is available regarding the identity or affiliation of the threat actor responsible for the incident.
Contact
- Registered BNIX customers can contact our Belnet Support.
- Private individuals who are not BNIX customers and who have sent emails to Belnet between 22 July 2026 and the morning of 25 September 2026 can contact our Data Protection Officer at dpo@belnet.be with questions regarding their personal data. We are prioritising support for our customers and end users. We therefore kindly ask for your patience and understanding if our response takes longer than usual.