From ba205f3d43e5686f3c01cc930b18cbc61a7782af Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen@gmail.com>
Date: Thu, 2 Jul 2026 20:10:35 +0100
Subject: [PATCH] ext/dom: fix use-after-free with XPath callback returning
 foreign-document node.

Fix GH-22554

A PHP XPath callback that returns a node belonging to a document created
inside the callback (e.g. $d->documentElement of a throwaway DOMDocument)
parks that node in the DOMXPath node_list to keep it alive. When a sibling
callback consumes a node navigated into that foreign document, the proxy
object was created with the DOMXPath's own dom as parent, so it took a
reference on the wrong document and none on the foreign one. On teardown the
foreign document could be freed while the proxy still referenced it.

Route the proxy factory through dom_xpath_intern_for_doc() so the created
object shares the ref_obj of the node's actual document, mirroring the
query-result path.

close GH-22562
---
 ext/dom/tests/gh22554.phpt | 38 ++++++++++++++++++++++++++++++++++++++
 ext/dom/xpath.c            |  3 ++-
 2 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 ext/dom/tests/gh22554.phpt

diff --git a/ext/dom/tests/gh22554.phpt b/ext/dom/tests/gh22554.phpt
new file mode 100644
index 000000000000..c8db1d87390b
--- /dev/null
+++ b/ext/dom/tests/gh22554.phpt
@@ -0,0 +1,38 @@
+--TEST--
+GH-22554 (Use-after-free when an XPath callback returns a node from a document created inside the callback)
+--CREDITS--
+waseem-cve
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$doc = new DOMDocument;
+$doc->loadXML('<root/>');
+
+$xp = new DOMXPath($doc);
+$xp->registerNamespace('my', 'my.ns');
+
+$xp->registerPHPFunctionNS('my.ns', 'include', function () {
+    $d = new DOMDocument;
+    $d->loadXML('<r><uaf/></r>');
+
+    return $d->documentElement;
+});
+
+$xp->registerPHPFunctionNS('my.ns', 'process', function ($arg) {
+    echo "process arg: ", get_class($arg[0]), " ", $arg[0]->nodeName, "\n";
+    return 'x';
+});
+
+$result = $xp->query('my:process(my:include()/uaf)');
+var_dump($result->length);
+unset($xp);
+
+echo "Done\n";
+
+?>
+--EXPECT--
+process arg: DOMElement uaf
+int(0)
+Done
diff --git a/ext/dom/xpath.c b/ext/dom/xpath.c
index bd9947b4ad10..dc9e1b852fae 100644
--- a/ext/dom/xpath.c
+++ b/ext/dom/xpath.c
@@ -77,7 +77,8 @@ static void dom_xpath_proxy_factory(xmlNodePtr node, zval *child, dom_object *in
 
 	ZEND_ASSERT(node->type != XML_NAMESPACE_DECL);
 
-	php_dom_create_object(node, child, intern);
+	dom_xpath_object *xobj = php_xpath_obj_from_obj(&intern->std);
+	php_dom_create_object(node, child, dom_xpath_intern_for_doc(xobj, node->doc));
 }
 
 static dom_xpath_object *dom_xpath_ext_fetch_intern(xmlXPathParserContextPtr ctxt)