ext/standard/var_unserializer.re in PHP 7.0.x before 7.0.21 and 7.1.x before 7.1.7 is prone to a heap use after free while unserializing untrusted data, related to the zval_get_type function in Zend/zend_types.h. Exploitation of this issue can have an unspecified impact on the integrity of PHP.
https://www.debian.org/security/2018/dsa-4080
https://bugs.php.net/bug.php?id=74101
https://access.redhat.com/errata/RHSA-2018:1296