Bug #75554 [Com]: session_regenerate_id() causes duplicate Set-Cookie header to be sent

Edit report at https://bugs.php.net/bug.php?id=75554&edit=1 ID: 75554 Comment by: tilmann dot bach at telekom dot de Reported by: arve at coretrek dot no Summary: session_regenerate_id() causes duplicate Set-Cookie header to be sent Status: Open Type: Bug Package: Session related Operating System: Linux Mint 18, Ubuntu 12.04 LTS PHP Version: 7.1.11 Block user comment: N Private report: N New Comment: I can confirm this BUG. This behavior is in contrast to the RFC: https://tools.ietf.org/html/rfc6265#section-4.1.1 "Servers SHOULD NOT include more than one Set-Cookie header field in the same response with the same cookie-name. (See Section 5.2 for how user agents handle this case.)" Previous Comments: ------------------------------------------------------------------------ [2017-11-22 12:37:24] arve at coretrek dot no Description: ------------ When calling session_start() and then session_regenerate_id(), PHP will send two Set-Cookie headers, one containing the old session id and the other containing the new session id. Testet on: * PHP 7.1.11 on Ubuntu 12.04 (installed via phpbrew) * PHP 7.0.22-0ubuntu0.16.04.1 on Linux Mint 18 Test script: --------------- First, create sessiontest.php: <?php session_start(); if (!isset($_SESSION['SessionInitiated'])) { session_regenerate_id(); $_SESSION['SessionInitiated'] = true; } ?> Then, access sessiontest.php through Apache and inspect response headers, e.g. by using curl: curl -sv http://localhost/sessiontest.php > /dev/null * Trying 127.0.1.1... * Connected to localhost (127.0.1.1) port 80 (#0) > GET /sessiontest.php HTTP/1.1 > Host: localhost > User-Agent: curl/7.47.0 > Accept: */* > < HTTP/1.1 200 OK < Date: Wed, 22 Nov 2017 12:07:52 GMT < Server: Apache/2.4.18 (Ubuntu) < Set-Cookie: PHPSESSID=8676mem4p76uka76ta2qq072q1; path=/ < Expires: Thu, 19 Nov 1981 08:52:00 GMT < Cache-Control: no-store, no-cache, must-revalidate < Pragma: no-cache < Set-Cookie: PHPSESSID=rvud0d79be3oa77rnbag0lmgc2; path=/ < Content-Length: 0 < Content-Type: text/html; charset=UTF-8 Expected result: ---------------- Only send one Set-Cookie header (containing the new session id). Actual result: -------------- Two Set-Cookie headers are sent, one containing the old session id and the other containing the new session id. This confuses browsers and cause some browsers to continue using the old session cookie. In addition, if you call var_dump(headers_list()) at the end of the script, only ONE Set-Cookie header will be listed here, even though two headers are sent. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=75554&edit=1