diff --git a/.build/cassandra-build-deps-template.xml b/.build/cassandra-build-deps-template.xml
index 357325f8be..cc1a25a8c1 100644
--- a/.build/cassandra-build-deps-template.xml
+++ b/.build/cassandra-build-deps-template.xml
@@ -143,5 +143,17 @@
       <groupId>com.carrotsearch.randomizedtesting</groupId>
       <artifactId>randomizedtesting-runner</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.bouncycastle</groupId>
+      <artifactId>bcpkix-jdk18on</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.bouncycastle</groupId>
+      <artifactId>bcprov-jdk18on</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>org.bouncycastle</groupId>
+      <artifactId>bcutil-jdk18on</artifactId>
+    </dependency>
   </dependencies>
 </project>
diff --git a/.build/cassandra-deps-template.xml b/.build/cassandra-deps-template.xml
index 701a7730e6..ab98e36ab8 100644
--- a/.build/cassandra-deps-template.xml
+++ b/.build/cassandra-deps-template.xml
@@ -157,10 +157,6 @@
       <groupId>com.github.jbellis</groupId>
       <artifactId>jamm</artifactId>
     </dependency>
-    <dependency>
-      <groupId>org.bouncycastle</groupId>
-      <artifactId>bcpkix-jdk18on</artifactId>
-    </dependency>
     <dependency>
       <groupId>io.netty</groupId>
       <artifactId>netty-all</artifactId>
diff --git a/.build/parent-pom-template.xml b/.build/parent-pom-template.xml
index 21cc187d13..a3f507706c 100644
--- a/.build/parent-pom-template.xml
+++ b/.build/parent-pom-template.xml
@@ -805,7 +805,20 @@
       <dependency>
         <groupId>org.bouncycastle</groupId>
         <artifactId>bcpkix-jdk18on</artifactId>
-        <version>1.76</version>
+        <version>1.78</version>
+        <scope>test</scope>
+      </dependency>
+      <dependency>
+        <groupId>org.bouncycastle</groupId>
+        <artifactId>bcprov-jdk18on</artifactId>
+        <version>1.78</version>
+        <scope>test</scope>
+      </dependency>
+      <dependency>
+        <groupId>org.bouncycastle</groupId>
+        <artifactId>bcutil-jdk18on</artifactId>
+        <version>1.78</version>
+        <scope>test</scope>
       </dependency>
       <dependency>
         <groupId>io.netty</groupId>
diff --git a/CHANGES.txt b/CHANGES.txt
index 56e6cbd4a5..77689676b0 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 5.0-rc1
+ * Move bcpkix-jdk18on to build dependencies, update to 1.78 and explicitly enumerate transitive dependencies (CASSANDRA-19739)
  * Avoid streams in the common case for UpdateTransaction creation (CASSANDRA-19675)
  * Only wait until native_transport_timeout for dispatcher to finish (CASSANDRA-19697)
  * Disable chronicle analytics (CASSANDRA-19656)