Ubuntu Linux provides security patching for 5 years on each Long Term Support (LTS) release.
To help support and secure our Managed VPS clients that for whatever reason are stuck on older LTS releases past that 5 year mark, we are rolling out Ubuntu Expanded Security Maintenance (ESM) ubuntu.com/secur… as part of Ubuntu Pro. There will be a fee for this service eventually, and we will post a full news story about this soon, but at least until the start of the new year, it's free.