Mastodon flagship server hit by DDoS attack

On Monday, the flagship server of social networking software maker Mastodon was hit by a distributed denial-of-service attack. The incident targeted mastodon.social, which is the platform’s primary instance—a term used to describe a specific server running the Mastodon software. While the company deployed countermeasures to restore access to the site, Mastodon warned that some instability may continue to be seen as the attack is ongoing. According to Mastodon, the millions of malicious requests directed at the server are consistent with the pattern of a distributed denial-of-service (DDoS) attack, which works by sending massive amounts of junk web traffic to knock servers offline.

Despite the disruption to the main server, the broader network remained operational due to its structural design. Andy Piper, Mastodon’s head of communications, highlighted how this incident demonstrated the benefits of a distributed model. “This is a case where the decentralized nature of the Fediverse is a true advantage. Users with accounts on other Mastodon (or any other Fediverse) servers were completely unaffected, and in most cases, the outage would have been invisible to them — they have been able to access the network, read and share posts as usual,” Piper said. The Fediverse refers to the decentralized ecosystem of interconnected social networking servers.

The incident at Mastodon follows a similar cyberattack on Bluesky, another decentralized social network. Bluesky recently resolved much of its days-long outages following a lengthy DDoS attack. According to Bluesky’s updates, its service became stable on April 16, though the attack was still ongoing as of April 17. During that disruption, users who had moved their accounts to other providers on the same protocol as Bluesky, such as Blacksky, were unaffected. These incidents occur against a backdrop of increasingly powerful cyberattacks; network security company Cloudflare recently mitigated what is the largest DDoS attack to date, measuring a peak of 29.7 terabits per second.

Why it matters

The attack on Mastodon’s flagship server highlights the vulnerability of centralized instances within the decentralized Fediverse, while simultaneously demonstrating the network’s resilience.