dompdf.php in dompdf before 0.6.1, when DOMPDF_ENABLE_PHP is enabled, allows context-dependent attackers to bypass chroot protections and read arbitrary files via a PHP protocol and wrappers in the input_file parameter, as demonstrated by a php://filter/read=convert.base64-encode/resource in the input_file parameter.
https://github.com/dompdf/dompdf/commit/23a693993299e669306929e3d49a4a1f7b3fb028
https://explore.avertium.com/resource/lfi-rfi-escalation-to-rce