diff --git a/ext/libxml/libxml.c b/ext/libxml/libxml.c
index de42b176b3f..2e75d697296 100644
--- a/ext/libxml/libxml.c
+++ b/ext/libxml/libxml.c
@@ -342,7 +342,26 @@ PHP_LIBXML_API void php_libxml_node_free_list(xmlNodePtr node)
 					if (ptr->_private) {
 						const php_libxml_node_object *obj = ptr->_private;
 						if (!obj->document || obj->document->class_type < PHP_LIBXML_CLASS_MODERN) {
-							xmlReconciliateNs(curnode->doc, curnode);
+							if (LIBXML_VERSION < 21300 && UNEXPECTED(curnode->doc == NULL)) {
+								/* xmlReconciliateNs() in these versions just uses the document for xmlNewReconciledNs(),
+								 * which can create an oldNs xml namespace declaration via xmlSearchNs() -> xmlTreeEnsureXMLDecl(). */
+								xmlDoc dummy;
+								memset(&dummy, 0, sizeof(dummy));
+								dummy.type = XML_DOCUMENT_NODE;
+								curnode->doc = &dummy;
+								xmlReconciliateNs(curnode->doc, curnode);
+								curnode->doc = NULL;
+
+								/* Append oldNs to current node's nsDef, which can be at most one node. */
+								if (dummy.oldNs) {
+									ZEND_ASSERT(dummy.oldNs->next == NULL);
+									xmlNsPtr old = curnode->nsDef;
+									curnode->nsDef = dummy.oldNs;
+									dummy.oldNs->next = old;
+								}
+							} else {
+								xmlReconciliateNs(curnode->doc, curnode);
+							}
 						}
 					}
 				}
diff --git a/ext/xmlreader/tests/gh19098.phpt b/ext/xmlreader/tests/gh19098.phpt
new file mode 100644
index 00000000000..13a6eda328f
--- /dev/null
+++ b/ext/xmlreader/tests/gh19098.phpt
@@ -0,0 +1,44 @@
+--TEST--
+GH-19098 (libxml<2.13 segmentation fault caused by php_libxml_node_free)
+--EXTENSIONS--
+xmlreader
+dom
+--FILE--
+<?php
+
+$xml_reader = \XMLReader::XML('
+<sparql xmlns="http://www.w3.org/2005/sparql-results#">
+ <results>
+  <result><binding xml:id="foo" xmlns:custom="urn:custom" custom:foo="bar" name="s"><uri/></binding></result>
+ </results>
+</sparql>');
+
+$success = $xml_reader->next("sparql");
+
+$success = $xml_reader->read();
+$success = $xml_reader->next("results");
+
+while ($xml_reader->read()) {
+  if ($xml_reader->next("result")) {
+    $result_as_dom_node = $xml_reader->expand();
+    $child = $result_as_dom_node->firstChild;
+    unset($result_as_dom_node);
+    var_dump($child->namespaceURI);
+    foreach ($child->attributes as $attr) {
+      var_dump($attr->namespaceURI);
+    }
+    $doc = new DOMDocument;
+    $doc->adoptNode($child);
+    echo $doc->saveXML($child), "\n";
+    unset($child);
+    break;
+  }
+}
+
+?>
+--EXPECT--
+string(38) "http://www.w3.org/2005/sparql-results#"
+string(36) "http://www.w3.org/XML/1998/namespace"
+string(10) "urn:custom"
+NULL
+<default:binding xmlns:custom="urn:custom" xmlns:default="http://www.w3.org/2005/sparql-results#" xml:id="foo" custom:foo="bar" name="s"><default:uri/></default:binding>