// Module included in the following assemblies:
//
// * post_installation_configuration/day_2_core_cnf_clusters/updating/update-rhacm-talm-overview.adoc

:_mod-docs-content-type: CONCEPT
[id="core-cluster-upgrade-scenario-z-stream_{context}"]
= Z-stream updates

[role="_abstract"]
Z-stream updates apply patch releases within a minor version, such as updating from 4.20.0 to 4.20.1.
These updates address security vulnerabilities and bug fixes without introducing new features.

Z-stream releases follow a weekly cadence and should be applied as soon as they become available.
The risk profile for z-stream updates is low because they do not include API changes or feature modifications.

The following list describes use cases for z-stream updates:

* Applying critical security patches (CVEs)
* Resolving production bugs identified in the current minor version
* Maintaining compliance with security policies that require timely patching
* Performing regular maintenance updates during normal operating windows

When configured with proper pod disruption budgets, z-stream updates cause minimal workload disruption.
Control plane nodes update in a rolling fashion, and worker nodes update one at a time or in small batches.
