Long-term support (LTS) is a maintenance model that keeps a software branch receiving security fixes, bug fixes, and often backported changes for an extended period. Instead of forcing constant upgrades to new major versions, vendors or communities keep one branch stable and patch it for years.
In cyber security, LTS matters because many servers, appliances, and embedded systems need predictable behavior as well as protection. Defenders use LTS to reduce downtime and limit regression risk while still closing known vulnerabilities. Attackers, in turn, often look for unsupported or neglected branches where public flaws remain unpatched. The key operational question is not just whether software has an LTS label, but whether the organization is actually tracking support dates, applying updates promptly, and replacing versions before support ends.