diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index bc7bdfb..c60be00 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -40994,8 +40994,8 @@
 class _ValidatingTreeSanitizer implements NodeTreeSanitizer {
   NodeValidator validator;
 
-  /// Did we modify the tree by removing anything.
-  bool modifiedTree = false;
+  /// Number of tree modifications this instance has made.
+  int numTreeModifications = 0;
   _ValidatingTreeSanitizer(this.validator) {}
 
   void sanitizeTree(Node node) {
@@ -41026,12 +41026,12 @@
       }
     }
 
-    modifiedTree = false;
-    walk(node, null);
-    while (modifiedTree) {
-      modifiedTree = false;
+    // Walk the tree until no new modifications are added to the tree.
+    var previousTreeModifications;
+    do {
+      previousTreeModifications = numTreeModifications;
       walk(node, null);
-    }
+    } while (previousTreeModifications != numTreeModifications);
   }
 
   /// Aggressively try to remove node.
@@ -41039,7 +41039,7 @@
     // If we have the parent, it's presumably already passed more sanitization
     // or is the fragment, so ask it to remove the child. And if that fails
     // try to set the outer html.
-    modifiedTree = true;
+    numTreeModifications++;
     if (parent == null || parent != node.parentNode) {
       node.remove();
     } else {
diff --git a/tests/lib/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart b/tests/lib/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
index 5a3d0f2..2d7205c 100644
--- a/tests/lib/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
+++ b/tests/lib/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
@@ -453,6 +453,20 @@
             "<input id='bad' onmouseover='alert(1)'>",
         "");
 
+    // Walking templates triggers a recursive sanitization call, which shouldn't
+    // invalidate the information collected from the previous visit of the later
+    // nodes in the walk.
+    testHtml(
+        'DOM clobbering with recursive sanitize call using templates',
+        validator,
+        "<form><div>"
+            "<input id=childNodes />"
+            "<template></template>"
+            "<input id=childNodes name=lastChild />"
+            "<img id=exploitImg src=0 onerror='alert(1)' />"
+            "</div></form>",
+        "");
+
     test('tagName makes containing form invalid', () {
       var fragment = document.body!.createFragment(
           "<form onmouseover='alert(2)'><input name='tagName'>",
diff --git a/tests/lib_2/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart b/tests/lib_2/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
index 1b3ea60..ee31868 100644
--- a/tests/lib_2/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
+++ b/tests/lib_2/html/node_validator_important_if_you_suppress_make_the_bug_critical_test.dart
@@ -478,6 +478,20 @@
         "<input id='bad' onmouseover='alert(1)'>",
         "");
 
+    // Walking templates triggers a recursive sanitization call, which shouldn't
+    // invalidate the information collected from the previous visit of the later
+    // nodes in the walk.
+    testHtml(
+        'DOM clobbering with recursive sanitize call using templates',
+        validator,
+        "<form><div>"
+          "<input id=childNodes />"
+          "<template></template>"
+          "<input id=childNodes name=lastChild />"
+          "<img id=exploitImg src=0 onerror='alert(1)' />"
+          "</div></form>",
+        "");
+
     test('tagName makes containing form invalid', () {
       var fragment = document.body.createFragment(
           "<form onmouseover='alert(2)'><input name='tagName'>",
diff --git a/tools/dom/src/Validators.dart b/tools/dom/src/Validators.dart
index 0c45b8c..1fbafbd 100644
--- a/tools/dom/src/Validators.dart
+++ b/tools/dom/src/Validators.dart
@@ -158,8 +158,8 @@
 class _ValidatingTreeSanitizer implements NodeTreeSanitizer {
   NodeValidator validator;
 
-  /// Did we modify the tree by removing anything.
-  bool modifiedTree = false;
+  /// Number of tree modifications this instance has made.
+  int numTreeModifications = 0;
   _ValidatingTreeSanitizer(this.validator) {}
 
   void sanitizeTree(Node node) {
@@ -190,12 +190,12 @@
       }
     }
 
-    modifiedTree = false;
-    walk(node, null);
-    while (modifiedTree) {
-      modifiedTree = false;
+    // Walk the tree until no new modifications are added to the tree.
+    var previousTreeModifications;
+    do {
+      previousTreeModifications = numTreeModifications;
       walk(node, null);
-    }
+    } while (previousTreeModifications != numTreeModifications);
   }
 
   /// Aggressively try to remove node.
@@ -203,7 +203,7 @@
     // If we have the parent, it's presumably already passed more sanitization
     // or is the fragment, so ask it to remove the child. And if that fails
     // try to set the outer html.
-    modifiedTree = true;
+    numTreeModifications++;
     if (parent == null || parent != node.parentNode) {
       node.remove();
     } else {