Large distributed denial-of-service attacks knocked parts of Threema’s secure messaging service offline this week, disrupting message delivery for users of the hosted service. Threema said the attacks hit both its own infrastructure and colocation partner Nine, with attackers changing traffic patterns to evade defenses; Threema On-Prem customers were not affected because they run their own infrastructure.
Why it matters: This matters to people and organizations that rely on Threema for secure communications, because service outages can interrupt urgent or sensitive messaging even when no data breach is reported. Hosted customers should review continuity plans and watch for vendor updates, while security teams should note the added DDoS protections and the difference between hosted and on-premises exposure.
SecurityWeek News
2026.08.21
95% relevant
It adds that Threema responded by deploying upstream traffic filtering through its colocation partner to block malicious traffic before it reached and overloaded its servers.
Ionut Ilascu
2026.08.16
100% relevant
This article establishes the event: Threema confirmed that large-scale DDoS attacks, not just a generic network outage, caused multi-day disruptions to its hosted secure messaging service.
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