Shibboleth XMLTooling-C before 1.6.3, as used in Shibboleth Service Provider before 2.6.0 on Windows and other products, mishandles digital signatures of user attribute data, which allows remote attackers to obtain sensitive information or conduct impersonation attacks via a crafted DTD.
https://www.debian.org/security/2018/dsa-4085
https://shibboleth.net/community/advisories/secadv_20180112.txt
https://lists.debian.org/debian-security-announce/2018/msg00007.html
https://lists.debian.org/debian-lts-announce/2018/01/msg00016.html