In LibSass 3.5.5, a NULL Pointer Dereference in the function Sass::Selector_List::populate_extends in SharedPtr.hpp (used by ast.cpp and ast_selectors.cpp) may cause a Denial of Service (application crash) via a crafted sass input file.
https://github.com/sass/libsass/issues/2779
http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00027.html
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00051.html
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00047.html