[eyupcanakman]

The filter.c line this PR added came into PHP-8.5 with the merge of GH-25349, so the rebase leaves only the test.
It covers the two cases that leaked, a nested array failing under FILTER_THROW_ON_FAILURE and a callback that throws on a nested element.

[devnexen]

it might be possible to simplify a tad

--- a/ext/filter/tests/filter_var_array_exception_leak.phpt
+++ b/ext/filter/tests/filter_var_array_exception_leak.phpt
@@ -4,34 +4,23 @@
 filter
 --FILE--
 <?php
-function leakcheck(callable $fn): bool {
-    $fn();
-    $before = memory_get_usage();
-    for ($i = 0; $i < 2000; $i++) {
-        $fn();
-    }
-    return memory_get_usage() - $before === 0;
+try {
+    filter_var_array(['a' => ['1', 'x']], ['a' => ['filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_REQUIRE_ARRAY | FILTER_THROW_ON_FAILURE]]);
+} catch (Filter\FilterFailedException $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
 }

-var_dump(leakcheck(function () {
-    try {
-        filter_var_array(['a' => ['1', 'x']], ['a' => ['filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_REQUIRE_ARRAY | FILTER_THROW_ON_FAILURE]]);
-    } catch (Filter\FilterFailedException $e) {
-    }
-}));
-
-var_dump(leakcheck(function () {
-    try {
-        filter_var_array(['a' => ['1', 'x']], ['a' => ['filter' => FILTER_CALLBACK, 'options' => function ($value) {
-            if ($value === 'x') {
-                throw new Exception('callback failed');
-            }
-            return $value;
-        }]]);
-    } catch (Exception $e) {
-    }
-}));
+try {
+    filter_var_array(['a' => ['1', 'x']], ['a' => ['filter' => FILTER_CALLBACK, 'options' => function ($value) {
+        if ($value === 'x') {
+            throw new Exception('callback failed');
+        }
+        return $value;
+    }]]);
+} catch (Exception $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
 ?>
 --EXPECT--
-bool(true)
-bool(true)
+Filter\FilterFailedException: filter validation failed: filter int not satisfied by 'x'
+Exception: callback failed

[eyupcanakman]

Done, used your version. This is test-only now, the description says why.