Repatching

Repatching is the process of reapplying or updating patches that have already been released and installed on a software system, device, or firmware. It may involve issuing a subsequent patch that supersedes earlier updates, correcting issues found after deployment, or reapplying a patch to environments where the initial update did not install correctly.

Contexts and scope can include operating systems, applications, embedded devices, firmware, and game patches. Repatching is typically used when a released patch introduces new problems, does not fully resolve the targeted issue, or when new vulnerabilities are discovered that require a revised fix. It can also occur when deployment problems, compatibility concerns, or configuration drift leave systems effectively unpatched.

Common workflow involves identifying the need for a repatch through monitoring, testing, and vulnerability advisories; developing a new patch or delta patch; testing for regressions and compatibility; releasing the repatch as a hotfix or as part of a new patch bundle; deploying the update through staged or automated rollout; and verifying success and maintaining records.

Techniques associated with repatching include delta or incremental patches (to minimize disruption), cumulative patches (to bundle fixes), and patch sequencing to manage dependencies. Patch management tools and processes are often used to track patch status, coordinate rollouts, and ensure integrity through signing and verification.

Risks include patch conflicts, dependency issues, version drift, and increased maintenance overhead. When executed carefully, repatching can restore security, fix residual bugs, and improve stability beyond what the initial patch achieved.