diff --git a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFEndnotes.java b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFEndnotes.java
index 549a746fc8..2c3d6d7626 100644
--- a/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFEndnotes.java
+++ b/poi-ooxml/src/main/java/org/apache/poi/xwpf/usermodel/XWPFEndnotes.java
@@ -123,6 +123,11 @@ public class XWPFEndnotes extends XWPFAbstractFootnotesEndnotes {
 
     @Override
     protected void commit() throws IOException {
+        // cannot save anything if class is not initialized fully
+        if (ctEndnotes == null) {
+            return;
+        }
+
         XmlOptions xmlOptions = new XmlOptions(DEFAULT_XML_OPTIONS);
         xmlOptions.setSaveSyntheticDocumentElement(new QName(CTEndnotes.type.getName().getNamespaceURI(), "endnotes"));
         PackagePart part = getPackagePart();
diff --git a/test-data/document/clusterfuzz-testcase-minimized-POIXWPFFuzzer-4961551840247808.docx b/test-data/document/clusterfuzz-testcase-minimized-POIXWPFFuzzer-4961551840247808.docx
new file mode 100644
index 0000000000..cb604f0cc5
Binary files /dev/null and b/test-data/document/clusterfuzz-testcase-minimized-POIXWPFFuzzer-4961551840247808.docx differ
diff --git a/test-data/spreadsheet/stress.xls b/test-data/spreadsheet/stress.xls
index cfc460f7d9..86981ef7c1 100644
Binary files a/test-data/spreadsheet/stress.xls and b/test-data/spreadsheet/stress.xls differ