In Laravel Framework through 5.5.40 and 5.6.x through 5.6.29, remote code execution might occur as a result of an unserialize call on a potentially untrusted X-XSRF-TOKEN value. This involves the decrypt method in Illuminate/Encryption/Encrypter.php and PendingBroadcast in gadgetchains/Laravel/RCE/3/chain.php in phpggc. The attacker must know the application key, which normally would never occur, but could happen if the attacker previously had privileged access or successfully accomplished a previous attack.

In Laravel framework through 5.5.21, remote attackers can obtain sensitive information (such as externally usable passwords) via a direct request for the /.env URI. NOTE: this CVE is only about Laravel framework's writeNewEnvironmentFileWith function in src/Illuminate/Foundation/Console/KeyGenerateCommand.php, which uses file_put_contents without restricting the .env permissions. The .env filename is not used exclusively by Laravel framework.