Rebuild and redeploy means taking updated source code or a patched dependency, compiling it into a new artifact such as a JAR, container image, or package, and then releasing that artifact into a test or production environment. It is more than copying files over an old system: the running software must be recreated from the fixed build so the change is actually present in what users execute.
This matters in cybersecurity because many vulnerabilities are only removed after the vulnerable version disappears from every build output, image, and deployment. In practice, defenders use rebuild and redeploy to turn a library patch, configuration fix, or security hardening change into real protection. Attackers benefit when teams skip this step, because old artifacts, cached images, and forgotten services can stay exposed even after the source repository is updated. Strong CI/CD pipelines, SBOM tracking, and dependency scanning help teams identify every place a rebuild is needed.