The object_common1 function in ext/standard/var_unserializer.c in PHP before 5.6.30, 7.0.x before 7.0.15, and 7.1.x before 7.1.1 allows remote attackers to cause a denial of service (buffer over-read and application crash) via crafted serialized data that is mishandled in a finish_nested_data call.
http://php.net/ChangeLog-5.php
http://php.net/ChangeLog-7.php
https://access.redhat.com/errata/RHSA-2018:1296
https://bugs.php.net/bug.php?id=73825
https://github.com/php/php-src/commit/16b3003ffc6393e250f069aa28a78dc5a2c064b2
https://security.gentoo.org/glsa/201702-29
https://security.netapp.com/advisory/ntap-20180112-0001/
https://www.tenable.com/security/tns-2017-04