diff --git a/zk/src/main/java/org/zkoss/zk/ui/http/ExecutionImpl.java b/zk/src/main/java/org/zkoss/zk/ui/http/ExecutionImpl.java
index aac06f1167..005a24186d 100644
--- a/zk/src/main/java/org/zkoss/zk/ui/http/ExecutionImpl.java
+++ b/zk/src/main/java/org/zkoss/zk/ui/http/ExecutionImpl.java
@@ -317,6 +317,8 @@ public void setVoided(boolean voided) {
}
public String encodeURL(String uri) {
+ if (uri == null || uri.isEmpty()) // ZK-5598
+ return uri;
try {
String encodedURL = Encodes.encodeURL(_ctx, _request, _response, uri);
String zkHostURL = (String) getDesktop().getAttribute("org.zkoss.desktop.auHost");
diff --git a/zkdoc/release-note b/zkdoc/release-note
index c9594307cd..7ceb25507e 100644
--- a/zkdoc/release-note
+++ b/zkdoc/release-note
@@ -18,6 +18,7 @@ ZK 10.0.0
ZK-5522: CommonFns.formatNumber() doesn't handle null as javadoc mentions
ZK-5569: Radiogroup onCheck event type mismatch
ZK-5161: page directive's attributes are not encoded before rendering into HTML
+ ZK-5598: CKEditor requests ExecutionImpl.encodeURL with null value, causes NPE in embedded mode
* Upgrade Notes
+ Upgrade commons-fileupload to commons-fileupload2-javax 2.0.0-M1 and commons-io to 2.13.0 to support jakarta-friendly uploads
diff --git a/zktest/src/main/webapp/test2/B100-ZK-5598.html b/zktest/src/main/webapp/test2/B100-ZK-5598.html
new file mode 100644
index 0000000000..e9197302ea
--- /dev/null
+++ b/zktest/src/main/webapp/test2/B100-ZK-5598.html
@@ -0,0 +1,26 @@
+
+
+
+
+
+
+
+
+ Set Library Property org.zkoss.web.servlet.http.embedded.enabled to true in zk.xml to enable embedded mode.
+ If you didn't see the ckeditor below, the bug still exist
+ (This bug triggered when use absolute-path to embedded a zul.
+
+
+
+
\ No newline at end of file
diff --git a/zktest/src/main/webapp/test2/B100-ZK-5598.zul b/zktest/src/main/webapp/test2/B100-ZK-5598.zul
new file mode 100644
index 0000000000..ce1255c8d4
--- /dev/null
+++ b/zktest/src/main/webapp/test2/B100-ZK-5598.zul
@@ -0,0 +1,16 @@
+
+
+
+
+
\ No newline at end of file
diff --git a/zktest/src/main/webapp/test2/config.properties b/zktest/src/main/webapp/test2/config.properties
index 0135b74e34..0a08371caf 100644
--- a/zktest/src/main/webapp/test2/config.properties
+++ b/zktest/src/main/webapp/test2/config.properties
@@ -3109,6 +3109,7 @@ B90-ZK-4431.zul=A,E,Multislider
##zats##B100-ZK-5522.zul=A,E,CommonFns,formatNumber
##zats##B100-ZK-5569.zul=A,E,Radiogroup,onCheck
##zats##B100-ZK-5161.zul=A,E,XSS,Security,Page
+##Manually##B100-ZK-5598.zul=A,E,CKEditor,Embedded,NPE
##
# Features - 3.0.x version