diff --git a/ext/standard/io_poll.c b/ext/standard/io_poll.c
index f01f8236d511..c500247dc8be 100644
--- a/ext/standard/io_poll.c
+++ b/ext/standard/io_poll.c
@@ -2,13 +2,11 @@
    +----------------------------------------------------------------------+
    | Copyright (c) The PHP Group                                          |
    +----------------------------------------------------------------------+
-   | This source file is subject to version 3.01 of the PHP license,      |
-   | that is bundled with this package in the file LICENSE, and is        |
-   | available through the world-wide-web at the following url:           |
-   | https://www.php.net/license/3_01.txt                                 |
-   | If you did not receive a copy of the PHP license and are unable to   |
-   | obtain it through the world-wide-web, please send a note to          |
-   | license@php.net so we can mail you a copy immediately.               |
+   | This source file is subject to the Modified BSD License that is      |
+   | bundled with this package in the file LICENSE, and is available      |
+   | through the World Wide Web at <https://www.php.net/license/>.        |
+   |                                                                      |
+   | SPDX-License-Identifier: BSD-3-Clause                                |
    +----------------------------------------------------------------------+
    | Author: Jakub Zelenka <bukka@php.net>                                |
    +----------------------------------------------------------------------+
diff --git a/ext/standard/tests/streams/stream_context_set_option_no_default_leak.phpt b/ext/standard/tests/streams/stream_context_set_option_no_default_leak.phpt
new file mode 100644
index 000000000000..788b6d8a4676
--- /dev/null
+++ b/ext/standard/tests/streams/stream_context_set_option_no_default_leak.phpt
@@ -0,0 +1,29 @@
+--TEST--
+stream_context_set_option() on a context-less stream must not leak into the default context
+--FILE--
+<?php
+$a = fopen('php://memory', 'r+');
+stream_context_set_option($a, 'http', 'filename', 'test.txt');
+
+// The default context must stay untouched.
+var_dump(stream_context_get_options(stream_context_get_default()));
+
+// A later context-less stream must not inherit the option.
+$b = fopen('php://memory', 'r+');
+var_dump(stream_context_get_options($b));
+
+// The stream the option was set on keeps it for itself.
+var_dump(stream_context_get_options($a));
+?>
+--EXPECT--
+array(0) {
+}
+array(0) {
+}
+array(1) {
+  ["http"]=>
+  array(1) {
+    ["filename"]=>
+    string(8) "test.txt"
+  }
+}
diff --git a/main/streams/php_stream_errors.h b/main/streams/php_stream_errors.h
index c55c06e37f25..1642a6bdabd7 100644
--- a/main/streams/php_stream_errors.h
+++ b/main/streams/php_stream_errors.h
@@ -2,13 +2,11 @@
    +----------------------------------------------------------------------+
    | Copyright (c) The PHP Group                                          |
    +----------------------------------------------------------------------+
-   | This source file is subject to version 3.01 of the PHP license,      |
-   | that is bundled with this package in the file LICENSE, and is        |
-   | available through the world-wide-web at the following url:           |
-   | https://www.php.net/license/3_01.txt                                 |
-   | If you did not receive a copy of the PHP license and are unable to   |
-   | obtain it through the world-wide-web, please send a note to          |
-   | license@php.net so we can mail you a copy immediately.               |
+   | This source file is subject to the Modified BSD License that is      |
+   | bundled with this package in the file LICENSE, and is available      |
+   | through the World Wide Web at <https://www.php.net/license/>.        |
+   |                                                                      |
+   | SPDX-License-Identifier: BSD-3-Clause                                |
    +----------------------------------------------------------------------+
    | Authors: Jakub Zelenka <bukka@php.net>                               |
    +----------------------------------------------------------------------+
diff --git a/main/streams/stream_errors.c b/main/streams/stream_errors.c
index 3d7056c44d1e..72f7428594c3 100644
--- a/main/streams/stream_errors.c
+++ b/main/streams/stream_errors.c
@@ -2,13 +2,11 @@
    +----------------------------------------------------------------------+
    | Copyright (c) The PHP Group                                          |
    +----------------------------------------------------------------------+
-   | This source file is subject to version 3.01 of the PHP license,      |
-   | that is bundled with this package in the file LICENSE, and is        |
-   | available through the world-wide-web at the following url:           |
-   | https://www.php.net/license/3_01.txt                                 |
-   | If you did not receive a copy of the PHP license and are unable to   |
-   | obtain it through the world-wide-web, please send a note to          |
-   | license@php.net so we can mail you a copy immediately.               |
+   | This source file is subject to the Modified BSD License that is      |
+   | bundled with this package in the file LICENSE, and is available      |
+   | through the World Wide Web at <https://www.php.net/license/>.        |
+   |                                                                      |
+   | SPDX-License-Identifier: BSD-3-Clause                                |
    +----------------------------------------------------------------------+
    | Authors: Jakub Zelenka <bukka@php.net>                               |
    +----------------------------------------------------------------------+
diff --git a/main/streams/streams.c b/main/streams/streams.c
index 715bbcfe0371..171748e6a08a 100644
--- a/main/streams/streams.c
+++ b/main/streams/streams.c
@@ -2248,7 +2248,12 @@ PHPAPI php_stream *_php_stream_open_wrapper_ex(const char *path, const char *mod
 		stream->open_filename = __zend_orig_filename ? __zend_orig_filename : __zend_filename;
 		stream->open_lineno = __zend_orig_lineno ? __zend_orig_lineno : __zend_lineno;
 #endif
-		if (stream->ctx == NULL && context != NULL && !persistent) {
+		/* Attach an explicitly provided context to the stream, but never the
+		 * default context: sharing it by reference would let a later
+		 * stream_context_set_option() on the stream mutate the global default
+		 * context, leaking options into every other stream. Stream errors fall
+		 * back to the default context on their own when the stream has none. */
+		if (stream->ctx == NULL && context != NULL && context != FG(default_context) && !persistent) {
 			php_stream_context_set(stream, context);
 		}
 	}