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DDoS Attacks Cause Major Threema Outages

Securityaffairs.Co •Pierluigi Paganini • August 16, 2026

Large DDoS attacks disrupted Threema, causing severe communication outages. Threema On-Prem users were unaffected by the attacks. Threema suffered multiple large-scale DDoS attacks that disrupted its secure messaging service and caused severe communication issues. Organizations using Threema On-Prem were not affected, as their deployments run on their own infrastructure. Threema is a Swiss paid secure […]

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Large-Scale DDoS Attacks Disrupt Threema Messaging Service Threema, a secure messaging service, experienced significant disruptions due to multiple large-scale DDoS attacks earlier this week. Users reported outages starting on August 15, 2026, particularly affecting those in Switzerland, India, and China. Organizations using Threema On-Prem were unaffected as they operate on their own infrastructure. The attacks were characterized by a constantly changing pattern, making them difficult to mitigate. Threema confirmed that both its service and its colocation partner, Nine, were targeted. Users faced intermittent outages, and the company had to take its system status page offline due to unrelated technical issues. To prevent future incidents, Threema has implemented specialized DDoS protection measures. The company communicated with business customers about the unstable service conditions during the attacks. 4 sources 65

DDoS Attacks Cause Major Threema Outages

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Attack Types (1)

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