In LibSass prior to 3.5.5, Sass::Eval::operator()(Sass::Binary_Expression*) inside eval.cpp allows attackers to cause a denial-of-service resulting from stack consumption via a crafted sass file, because of certain incorrect parsing of '%' as a modulo operator in parser.cpp.
https://github.com/sass/libsass/issues/2659
https://github.com/sass/libsass/commit/210fdff7a65370c2ae24e022a2b35da8c423cc5f
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