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ext/session: validate session id just before sending cookie #25082

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9 changes: 9 additions & 0 deletions ext/session/session.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1493,6 +1493,15 @@ static zend_result php_session_send_cookie(void)

ZEND_ASSERT(strpbrk(ZSTR_VAL(PS(session_name)), SESSION_FORBIDDEN_CHARS) == NULL);

/* Validate the session ID again right before it is sent. The ID may have
* been corrupted in memory after it was initially validated, and sending
* it in a cookie could leak the corrupted contents. Do not fail the
* session here, as user save handlers may use IDs outside the default
* charset. */
if (UNEXPECTED(php_session_valid_key_ex(PS(id)) == FAILURE)) {
return SUCCESS;
}

/* URL encode id because it might be user supplied */
e_id = php_url_encode(ZSTR_VAL(PS(id)), ZSTR_LEN(PS(id)));

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25 changes: 25 additions & 0 deletions ext/session/tests/session_id_invalid_cookie.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
--TEST--
Invalid session IDs are not sent in the session cookie
--EXTENSIONS--
session
--INI--
session.save_handler=files
session.save_path=
session.use_cookies=1
session.use_strict_mode=0
--CGI--
--FILE--
<?php
session_id("nulbug\0stillvalid");
var_dump(session_start());
foreach (headers_list() as $header) {
if (str_starts_with($header, "Set-Cookie:")) {
echo $header, "\n";
}
}
?>
--EXPECTF--
Warning: session_start(): Session ID is too long or contains illegal characters. Only the A-Z, a-z, 0-9, "-", and "," characters are allowed in %s on line %d

Warning: session_start(): Failed to read session data: files (path: ) in %s on line %d
bool(false)
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