diff --git a/modules/zstream-4-21-31.adoc b/modules/zstream-4-21-31.adoc
new file mode 100644
index 00000000000..3b118861161
--- /dev/null
+++ b/modules/zstream-4-21-31.adoc
@@ -0,0 +1,41 @@
+// Module included in the following assemblies:
+//
+// * release_notes/ocp-4-21-release-notes.adoc
+
+:_mod-docs-content-type: REFERENCE
+[id="zstream-4-21-31_{context}"]
+= RHBA-2026:60477 - {product-title} {product-version}.31 bug fix and security update
+
+Issued: 01 September 2026
+
+[role="_abstract"]
+{product-title} release {product-version}.31 is now available with updates to packages and images that fix several bugs.
+
+The following advisory contains the container images for this release:
+
+link:https://access.redhat.com/errata/RHBA-2026:60477[RHBA-2026:60477]
+
+The following advisory contains the RPM packages for this release:
+
+link:https://access.redhat.com/errata/RHBA-2026:xxxxx[RHBA-2026:xxxxx]
+
+Space precludes documenting all of the container images for this release. See the following Release Notes documentation for details about these changes:
+
+link:https://docs.redhat.com/en/documentation/openshift_container_platform/4.21/html/release_notes[{product-title} {product-version} Release Notes]
+
+This update includes the following images:
+
+[source,terminal]
+----
+$ oc adm release info 4.21.31 --pullspecs
+----
+
+[id="zstream-4-21-31-fixed-issues_{context}"]
+== Fixed issues
+
+* Previously the Go OpenSSL FIPS provider would potentially overwhelm libcrypto with concurrent requests leading to processes hitting the Go maxThreads limit of 10,000 and crashing. The Go OpenSSL FIPS provider has been updated to limit concurrent requests to libcrypto to 4x the number of CPUs buffering requests as lightweight Goroutines and avoiding the maxThreads limit preventing a crash. (link:https://issues.redhat.com/browse/OCPBUGS-112086[OCPBUGS-112086])
+
+[id="zstream-4-21-31-updating_{context}"]
+== Updating
+
+To update an {product-title} 4.21 cluster to this latest release, see xref:../updating/updating_a_cluster/updating-cluster-cli.adoc#updating-cluster-cli[Updating a cluster using the CLI].
diff --git a/release_notes/ocp-4-21-release-notes.adoc b/release_notes/ocp-4-21-release-notes.adoc
index 1378a3bc5ce..79f41dfb68d 100644
--- a/release_notes/ocp-4-21-release-notes.adoc
+++ b/release_notes/ocp-4-21-release-notes.adoc
@@ -47,6 +47,9 @@ include::modules/rn-ocp-release-notes-known-issues.adoc[leveloffset=+1]
 // Asynchronous errata updates
 include::modules/rn-async-errata.adoc[leveloffset=+1]
 
+// 4.21.31 RNs and updating
+include::modules/zstream-4-21-31.adoc[leveloffset=+2]
+
 // 4.21.30 RNs and updating
 include::modules/zstream-4-21-30.adoc[leveloffset=+2]