OSDOCS-22244: Add 4.18.55 z-stream release notes (advisory-only)

modules/zstream-4-18-55.adoc

@@ -0,0 +1,33 @@
+// Module included in the following assemblies:
+//
+// * release_notes/ocp-4-18-release-notes.adoc
+
+:_mod-docs-content-type: REFERENCE
+[id="zstream-4-18-55_{context}"]
+= RHSA-2026:65852 - {product-title} {product-version}.55 bug fix and security update
+
+Issued: 17 September 2026
+
+[role="_abstract"]
+{product-title} release {product-version}.55 is now available. The list of fixed issues that are included in the update is documented in the link:https://access.redhat.com/errata/RHSA-2026:65852[RHSA-2026:65852] advisory. The RPM packages that are included in the update are provided by the link:https://access.redhat.com/errata/RHSA-2026:66385[RHSA-2026:66385] advisory.
+
+Space precluded documenting all of the container images for this release in the advisory.
+
+You can view the container images in this release by running the following command:
+
+[source,terminal]
+----
+$ oc adm release info 4.18.55 --pullspecs
+----
+
+[id="zstream-4-18-55-fixed-issues_{context}"]
+== Fixed issues
+
+* Before this update, when using Agent-based installation, the IP collision validation sent Address Resolution Protocol (ARP) requests from all network interfaces to verify IP address availability. As a consequence, if proxy ARP was enabled on VLAN interfaces configured as gateways for cluster management and storage networks, the validation incorrectly interpreted the proxy ARP responses as IP address collisions, causing the cluster installation to fail. With this release, the validation correctly handles proxy ARP scenarios. As a result, cluster installations succeed when proxy ARP is configured on the gateway interfaces. (link:https://issues.redhat.com/browse/OCPBUGS-61058[OCPBUGS-61058])
+
+* Before this update, the Operator used the `reflect.DeepEqual` parameter for node label comparison which required an exact label match instead of Kubernetes label selector semantics. As a consequence, the `IngressNodeFirewallNodeState` objects were not created for nodes added after the Operator startup. With this release, the `reflect.DeepEqual` parameter is replaced with the `labels.SelectorFromSet().Matches()` parameter for correct Kubernetes label selector matching. As a result, the Operator correctly creates the `IngressNodeFirewallNodeState` object for dynamically added nodes and label changes. (link:https://issues.redhat.com/browse/OCPBUGS-106121[OCPBUGS-106121])
+
+[id="zstream-4-18-55-updating_{context}"]
+== Updating
+
+To update an {product-title} 4.18 cluster to this latest release, see xref:../updating/updating_a_cluster/updating-cluster-cli.adoc#updating-cluster-cli[Updating a cluster using the CLI].

release_notes/ocp-4-18-release-notes.adoc

@@ -3064,6 +3064,9 @@ As a workaround, you must manually reboot the failed host from the disk. (link:h
 // 4.18 about async
 include::modules/rn-async-errata.adoc[leveloffset=+1]
 
+// 4.18.55 RNs and updating
+include::modules/zstream-4-18-55.adoc[leveloffset=+2]
+
 // 4.18.54 RNs and updating
 include::modules/zstream-4-18-54.adoc[leveloffset=+2]