According to a Ubuntu discussion forum on AskUbuntu.com, URLs that remained unavailable include:

• security.ubuntu.com 
• jaas.ai
• archive.ubuntu.com
• canonical.com 
• maas.io
• blog.ubuntu.com
• developer.ubuntu.com
• Ubuntu Security API – CVEs
• Ubuntu Security API – Notices
• academy.canonical.com
• ubuntu.com
• portal.canonical.com
• assets.ubuntu.com

Ubuntu and Canonical infrastructure went down hours after researchers released potent exploit code that allowed untrusted users in data centers, university settings, and elsewhere to gain all-powerful root control of servers running virtually all Linux distributions, including Ubuntu. The outage has limited Ubuntu’s ability to communicate security guidance to affected users. As noted earlier, updates remain available from mirror sites.

Stressor sites, also known as booter sites, have operated for decades. The DDoS-as-a-service operators have come under the attention of law enforcement in multiple countries, but attempts to shut down this scourge have never succeeded.

It’s unclear why the infrastructure has remained unavailable for so long. There’s a wealth of DDoS protection services, at least one of which is free.

Post updated on May 4, 2026 to correct attribution to the list of affected Ubuntu sites.