In OpenSSL 1.1.0 before 1.1.0c, applications parsing invalid CMS structures can crash with a NULL pointer dereference. This is caused by a bug in the handling of the ASN.1 CHOICE type in OpenSSL 1.1.0 which can result in a NULL value being passed to the structure callback if an attempt is made to free certain invalid encodings. Only CHOICE structures using a callback which do not handle NULL value are affected.
https://www.openssl.org/news/secadv/20161110.txt
https://h20566.www2.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbhf03744en_us