From a1028ff49b3507558c9b81c074e0a7bdbda99309 Mon Sep 17 00:00:00 2001
From: Ilia Alshanetsky <ilia@ilia.ws>
Date: Sun, 14 Jun 2026 18:52:59 -0400
Subject: [PATCH] Fix GH-21682: reject ZipArchive serialization via
 __serialize()

ZipArchive wraps a libzip handle that cannot survive serialization:
serialize() produced a string that unserialized into an empty object
with numFiles 0, and that unserialize path was the bug72434
use-after-free vector. Add __serialize() and __unserialize() that throw,
so the base class rejects (un)serialization and the UAF is closed by
construction, while a subclass can still override both to round-trip
through closeString()/openString(). Move the bug72434 test to
ext/zip/tests since it now requires the zip extension.

Fixes GH-21682
---
 ext/standard/tests/strings/bug72434.phpt | 29 ---------------------
 ext/zip/php_zip.c                        | 25 ++++++++++++++++++
 ext/zip/php_zip.stub.php                 |  4 +++
 ext/zip/php_zip_arginfo.h                | 13 +++++++++-
 ext/zip/tests/bug72434.phpt              | 17 +++++++++++++
 ext/zip/tests/gh21682.phpt               | 16 ++++++++++++
 ext/zip/tests/gh21682_subclass.phpt      | 32 ++++++++++++++++++++++++
 7 files changed, 106 insertions(+), 30 deletions(-)
 delete mode 100644 ext/standard/tests/strings/bug72434.phpt
 create mode 100644 ext/zip/tests/bug72434.phpt
 create mode 100644 ext/zip/tests/gh21682.phpt
 create mode 100644 ext/zip/tests/gh21682_subclass.phpt

diff --git a/ext/standard/tests/strings/bug72434.phpt b/ext/standard/tests/strings/bug72434.phpt
deleted file mode 100644
index 6d64baa26fa7..000000000000
--- a/ext/standard/tests/strings/bug72434.phpt
+++ /dev/null
@@ -1,29 +0,0 @@
---TEST--
-Bug #72434: ZipArchive class Use After Free Vulnerability in PHP's GC algorithm and unserialize
---FILE--
-<?php
-// The following array will be serialized and this representation will be freed later on.
-$free_me = array(new StdClass());
-// Create our payload and unserialize it.
-$serialized_payload = 'a:3:{i:1;N;i:2;O:10:"ZipArchive":1:{s:8:"filename";'.serialize($free_me).'}i:1;R:4;}';
-$unserialized_payload = unserialize($serialized_payload);
-gc_collect_cycles();
-// The reference counter for $free_me is at -1 for PHP 7 right now.
-// Increment the reference counter by 1 -> rc is 0
-$a = $unserialized_payload[1];
-// Increment the reference counter by 1 again -> rc is 1
-$b = $a;
-// Trigger free of $free_me (referenced by $m[1]).
-unset($b);
-$fill_freed_space_1 = "filler_zval_1";
-$fill_freed_space_2 = "filler_zval_2";
-$fill_freed_space_3 = "filler_zval_3";
-$fill_freed_space_4 = "filler_zval_4";
-debug_zval_dump($unserialized_payload[1]);
-?>
---EXPECTF--
-array(1) refcount(3){
-  [0]=>
-  object(stdClass)#%d (0) refcount(1){
-  }
-}
diff --git a/ext/zip/php_zip.c b/ext/zip/php_zip.c
index 12344450678b..f231b3ad9ef2 100644
--- a/ext/zip/php_zip.c
+++ b/ext/zip/php_zip.c
@@ -25,6 +25,7 @@
 #include "ext/standard/php_filestat.h"
 #include "zend_attributes.h"
 #include "zend_interfaces.h"
+#include "zend_exceptions.h"
 #include "php_zip.h"
 #include "php_zip_arginfo.h"
 
@@ -1645,6 +1646,30 @@ PHP_METHOD(ZipArchive, count)
 }
 /* }}} */
 
+PHP_METHOD(ZipArchive, __serialize)
+{
+	ZEND_PARSE_PARAMETERS_NONE();
+
+	zend_throw_exception_ex(NULL, 0,
+		"Serialization of '%s' is not allowed, override __serialize() and __unserialize() to implement it",
+		ZSTR_VAL(Z_OBJCE_P(ZEND_THIS)->name));
+}
+
+PHP_METHOD(ZipArchive, __unserialize)
+{
+	zval *data;
+
+	ZEND_PARSE_PARAMETERS_START(1, 1)
+		Z_PARAM_ARRAY(data)
+	ZEND_PARSE_PARAMETERS_END();
+
+	(void) data;
+
+	zend_throw_exception_ex(NULL, 0,
+		"Unserialization of '%s' is not allowed, override __serialize() and __unserialize() to implement it",
+		ZSTR_VAL(Z_OBJCE_P(ZEND_THIS)->name));
+}
+
 /* {{{ clear the internal status */
 PHP_METHOD(ZipArchive, clearError)
 {
diff --git a/ext/zip/php_zip.stub.php b/ext/zip/php_zip.stub.php
index 49dd19e53553..2cece2791d1b 100644
--- a/ext/zip/php_zip.stub.php
+++ b/ext/zip/php_zip.stub.php
@@ -661,6 +661,10 @@ public function closeString(): string|false {}
     /** @tentative-return-type */
     public function count(): int {}
 
+    public function __serialize(): array {}
+
+    public function __unserialize(array $data): void {}
+
     /** @tentative-return-type */
     public function getStatusString(): string {}
 
diff --git a/ext/zip/php_zip_arginfo.h b/ext/zip/php_zip_arginfo.h
index faa6feb1cb1e..4f8366dc1512 100644
--- a/ext/zip/php_zip_arginfo.h
+++ b/ext/zip/php_zip_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit php_zip.stub.php instead.
- * Stub hash: d623efdfe5ac46f07aebf8fb120050c818f3d793 */
+ * Stub hash: 206d9be6640ee7e94d68d7e075ab61bf3188cab3 */
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_zip_open, 0, 0, 1)
 	ZEND_ARG_TYPE_INFO(0, filename, IS_STRING, 0)
@@ -63,6 +63,13 @@ ZEND_END_ARG_INFO()
 ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_ZipArchive_count, 0, 0, IS_LONG, 0)
 ZEND_END_ARG_INFO()
 
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_class_ZipArchive___serialize, 0, 0, IS_ARRAY, 0)
+ZEND_END_ARG_INFO()
+
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_class_ZipArchive___unserialize, 0, 1, IS_VOID, 0)
+	ZEND_ARG_TYPE_INFO(0, data, IS_ARRAY, 0)
+ZEND_END_ARG_INFO()
+
 ZEND_BEGIN_ARG_WITH_TENTATIVE_RETURN_TYPE_INFO_EX(arginfo_class_ZipArchive_getStatusString, 0, 0, IS_STRING, 0)
 ZEND_END_ARG_INFO()
 
@@ -326,6 +333,8 @@ ZEND_METHOD(ZipArchive, setPassword);
 ZEND_METHOD(ZipArchive, close);
 ZEND_METHOD(ZipArchive, closeString);
 ZEND_METHOD(ZipArchive, count);
+ZEND_METHOD(ZipArchive, __serialize);
+ZEND_METHOD(ZipArchive, __unserialize);
 ZEND_METHOD(ZipArchive, getStatusString);
 ZEND_METHOD(ZipArchive, clearError);
 ZEND_METHOD(ZipArchive, addEmptyDir);
@@ -406,6 +415,8 @@ static const zend_function_entry class_ZipArchive_methods[] = {
 	ZEND_ME(ZipArchive, close, arginfo_class_ZipArchive_close, ZEND_ACC_PUBLIC)
 	ZEND_ME(ZipArchive, closeString, arginfo_class_ZipArchive_closeString, ZEND_ACC_PUBLIC)
 	ZEND_ME(ZipArchive, count, arginfo_class_ZipArchive_count, ZEND_ACC_PUBLIC)
+	ZEND_ME(ZipArchive, __serialize, arginfo_class_ZipArchive___serialize, ZEND_ACC_PUBLIC)
+	ZEND_ME(ZipArchive, __unserialize, arginfo_class_ZipArchive___unserialize, ZEND_ACC_PUBLIC)
 	ZEND_ME(ZipArchive, getStatusString, arginfo_class_ZipArchive_getStatusString, ZEND_ACC_PUBLIC)
 	ZEND_ME(ZipArchive, clearError, arginfo_class_ZipArchive_clearError, ZEND_ACC_PUBLIC)
 	ZEND_ME(ZipArchive, addEmptyDir, arginfo_class_ZipArchive_addEmptyDir, ZEND_ACC_PUBLIC)
diff --git a/ext/zip/tests/bug72434.phpt b/ext/zip/tests/bug72434.phpt
new file mode 100644
index 000000000000..e2ccebad3754
--- /dev/null
+++ b/ext/zip/tests/bug72434.phpt
@@ -0,0 +1,17 @@
+--TEST--
+Bug #72434: ZipArchive class Use After Free Vulnerability in PHP's GC algorithm and unserialize
+--EXTENSIONS--
+zip
+--FILE--
+<?php
+$free_me = array(new StdClass());
+$serialized_payload = 'a:3:{i:1;N;i:2;O:10:"ZipArchive":1:{s:8:"filename";'.serialize($free_me).'}i:1;R:4;}';
+try {
+    $unserialized_payload = unserialize($serialized_payload);
+    var_dump($unserialized_payload);
+} catch (Exception $e) {
+    echo $e->getMessage() . "\n";
+}
+?>
+--EXPECT--
+Unserialization of 'ZipArchive' is not allowed, override __serialize() and __unserialize() to implement it
diff --git a/ext/zip/tests/gh21682.phpt b/ext/zip/tests/gh21682.phpt
new file mode 100644
index 000000000000..ee09c73e5c4d
--- /dev/null
+++ b/ext/zip/tests/gh21682.phpt
@@ -0,0 +1,16 @@
+--TEST--
+GH-21682 (ZipArchive serialization is rejected)
+--EXTENSIONS--
+zip
+--FILE--
+<?php
+$a = new ZipArchive();
+try {
+    serialize($a);
+    echo "ERROR: should have thrown\n";
+} catch (\Exception $e) {
+    echo $e->getMessage() . "\n";
+}
+?>
+--EXPECT--
+Serialization of 'ZipArchive' is not allowed, override __serialize() and __unserialize() to implement it
diff --git a/ext/zip/tests/gh21682_subclass.phpt b/ext/zip/tests/gh21682_subclass.phpt
new file mode 100644
index 000000000000..8c50dd4f3a24
--- /dev/null
+++ b/ext/zip/tests/gh21682_subclass.phpt
@@ -0,0 +1,32 @@
+--TEST--
+GH-21682 (ZipArchive subclass implements serialization via __serialize()/__unserialize())
+--EXTENSIONS--
+zip
+--FILE--
+<?php
+class MyArchive extends ZipArchive
+{
+    public function __serialize(): array
+    {
+        return ['data' => $this->closeString()];
+    }
+
+    public function __unserialize(array $data): void
+    {
+        $this->openString($data['data']);
+    }
+}
+
+$zip = new MyArchive();
+$zip->openString();
+$zip->addFromString('test1', 'abc123');
+
+$roundtrip = unserialize(serialize($zip));
+var_dump($roundtrip instanceof MyArchive);
+var_dump($roundtrip->numFiles);
+var_dump($roundtrip->getFromName('test1'));
+?>
+--EXPECT--
+bool(true)
+int(1)
+string(6) "abc123"