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<?php class Test { function __wakeup() { print "wakeup\n"; } } session_start(); session_decode('core|a:1:{s:23:"_session_validator_data";a:4:{s:11:"remote_addr";s:9:"127.0.0.1";s:8:"http_via";s:0:"";s:20:"http_x_forwarded_for";s:0:"";s:15:"http_user_agent";s:45:"}}test|O:4:"Test":0:{}fooo|a:1:{i:0;a:1:{s:5:";}}'); var_dump($_SESSION);
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.20, 7.2.0 - 7.2.33, 7.3.16 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array(1) { ["core"]=> array(1) { ["_session_validator_data"]=> array(4) { ["remote_addr"]=> string(9) "127.0.0.1" ["http_via"]=> string(0) "" ["http_x_forwarded_for"]=> string(0) "" ["http_user_agent"]=> string(45) "}}test|O:4:"Test":0:{}fooo|a:1:{i:0;a:1:{s:5:" } } }

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